U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone

USGS Publications Warehouse

Neymark, L.A.; Amelin, Y.; Paces, J.B.; Peterman, Z.E.

2002-01-01

Uranium, Th and Pb isotopes were analyzed in layers of opal and chalcedony from individual mm- to cm-thick calcite and silica coatings at Yucca Mountain, Nevada, USA, a site that is being evaluated for a potential high-level nuclear waste repository. These calcite and silica coatings on fractures and in lithophysal cavities in Miocene-age tuffs in the unsaturated zone (UZ) precipitated from descending water and record a long history of percolation through the UZ. Opal and chalcedony have high concentrations of U (10 to 780 ppm) and low concentrations of common Pb as indicated by large values of 206Pb/204Pb (up to 53,806), thus making them suitable for U-Pb age determinations. Interpretations of U-Pb isotope systems in opal samples at Yucca Mountain are complicated by the incorporation of excess 234U at the time of mineral formation, resulting in reverse discordance of U-Pb ages. However, the 207PB/235U ages are much less affected by deviation from initial secular equilibrium and provide reliable ages of most silica deposits between 0.6 and 9.8 Ma. For chalcedony subsamples showing normal age discordance, these ages may represent minimum times of deposition. Typically, 207Pb/235U ages are consistent with the microstratigraphy in the mineral coating samples, such that the youngest ages are for subsamples from outer layers, intermediate ages are from inner layers, and oldest ages are from innermost layers. 234U and 230Th in most silica layers deeper in the coatings are in secular equilibrium with 238U, which is consistent with their old age and closed system behavior during the past -0.5 Ma. The ages for subsamples of silica layers from different microstratigraphic positions in individual calcite and silica coating samples collected from lithophysal cavities in the welded part of the Topopah Spring Tuff yield slow long-term average growth rates of 1 to 5 mm/Ma. These data imply that the deeper parts of the UZ at Yucca Mountain maintained long-term hydrologic stability over the past 10 Ma. despite significant climate variations. U-Pb ages for subsamples of silica layers from different microstratigraphic positions in individual calcite and silica coating samples collected from fractures in the shallower part of the UZ (welded part of the overlying Tiva Canyon Tuff) indicate larger long-term average growth rates up to 23 mm/Ma and an absence of recently deposited materials (ages of outermost layers are 3-5 Ma.). These differences between the characteristics of the coatings for samples from the shallower and deeper parts of the UZ may indicate that the nonwelded tuffs (PTn), located between the welded parts of the Tiva Canyon and Topopah Spring Tuffs, play an important role in moderating UZ flow.

Secondary Mineral Deposits and Evidence of Past Seismicity and Heating of the Proposed Repository Horizon at Yucca Mountain, Nevada

USGS Publications Warehouse

Whelan, Josheph F.

2004-01-01

The Drift Degradation Analysis (DDA) (BSC, 2003) for the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, describes model simulations of the effects of pre- and post-closure seismicity and waste-induced heating on emplacement drifts. Based on probabilistic seismic hazard analyses of the intensity and frequency of future seismic events in the region (CRWMS M&O, 1998), the DDA concludes that future seismicity will lead to substantial damage to emplacement drifts, particularly those in the lithophysal tuffs, where some simulations predict complete collapse of the drift walls. Secondary mineral studies conducted by the U.S. Geological Survey since 1995 indicate that secondary calcite and silica have been deposited in some fractures and lithophysal cavities in the unsaturated zone (UZ) at Yucca Mountain during at least the past 10 million years (m.y.), and probably since the tuffs cooled to less than 100?C. Tuff fragments, likely generated by past seismic activity, have commonly been incorporated into the secondary mineral depositional sequences. Preliminary observations indicate that seismic activity has generated few, if any, tuff fragments during the last 2 to 4 m.y., which may be inconsistent with the predictions of drift-wall collapse described in the DDA. Whether or not seismicity-induced tuff fragmentation occurring at centimeter to decimeter scales in the fracture and cavity openings relates directly to failure of tuff walls in the 5.5-m-diameter waste emplacement drifts, the deposits do provide a potential record of the spatial and temporal distribution of tuff fragments in the UZ. In addition, the preservation of weakly attached coatings and (or) delicate, upright blades of calcite in the secondary mineral deposits provides an upper limit for ground motion during the late stage of deposition that might be used as input to future DDA simulations. Finally, bleaching and alteration at a few of the secondary mineral sites indicate that they were subjected to heated gases at approximately the temperatures expected from waste emplacement. These deposits provide at least limited textural and mineralogic analogs for waste-induced, high-humidity thermal alteration of emplacement drift wall rocks.

Prime Contract Awards by State or Country, Place and Contractor. Part 10 (Royal Oak, Michigan - Garwood, New Jersey), FY1991

DTIC Science & Technology

1991-01-01

C M M M M M m -0 a Iiia 0-40 e f3 00) a 2S 4ca * 0 co~ : i ag ~ :0 0 U qt 0 W U c EWI 044 U * U* * O M-4c𔃺 -0 us I LJ.E)(U 0 8N 00 U 0 U -4" U0)o -4...4444~~- CY4 -404 -4-I *-40 MfI0-4"< I CC0 .d(f =:I- NNi =(n =~OOOOOOOOOf .(Al =N =CU) m ag iIn0-40 II 4.z uz uz2zz u2 uzzzzzzzzzzzz uz uZ Qz uZr H I02...0000 11 02-4NOHm 0000000 000 0 0) 0) 00 00000J a u< I IW-4CN02H 00 0 00 -W - -- 4-1 1--- fIT M4 10002W )0 1aJ4 I’ I0-40IM 440244 44 -( Ag -< -4< -00

Single-site properties of U impurities doped in La2Zn17 (abstract)

NASA Astrophysics Data System (ADS)

Suzuki, H.; Anzai, K.; Takagi, S.

1997-04-01

Thermodynamic and transport properties of heavy Fermion (HF) U compounds show similar behavior to HF Ce compounds. Although most of the magnetic properties of HF Ce compounds can be qualitatively understood on the basis of the impurity Kondo model, no such consensus for HF U compounds has been reached. In addition to this, the single-site properties of U impurities are not understood so well, in contrast to the case of Ce impurities. Recent works for dilute U systems reported new features as are not seen in dilute Ce systems. We have investigated a dilute-U2Zn17 system of (La1-zUz)2Zn17 in order to reveal the single U ion site properties of this system by preparing single crystals. The impurity contributions to various physical quantities such as ρimp(T), χimp(T), and Cimp(T) can be scaled by the U concentration between z=0.025 and 0.05, and the system is considered as in the dilute limit still for z=0.05. The electrical resistivity shows the typical impurity-Kondo upturn at low temperatures. The electronic specific-heat coefficient is strongly enhanced (γimp≈1.5 J/K2 mole U) and about 4 times as large as that for dense U2Zn17. Suppressions of the Kondo effect by the magnetic field are seen in γimp(H) and magnetoresistance. The relatively large anisotropy in χimp(T) indicates an existence of the crystal field. These features of this system will be explained in terms of the Kondo effect in the presence of the crystal field.

THE FIRST PHOTOMETRIC INVESTIGATION OF THE NEGLECTED W-UMa-TYPE BINARY STAR UZ CMi

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, S.-B.; Li, K.; Liao, W.-P.

2013-04-15

UZ CMi was a W-UMa-type binary star found more than 80 years ago. However, it has been neglected in photometric investigations. Here, the first complete light curves in the B, V, R, and I bands are presented and analyzed using the Wilson and Devinney method. It is discovered that UZ CMi is a contact binary (f = 38.4({+-} 2.3)%) with a mass ratio of 0.45. The derived orbital inclination (i = 87 Degree-Sign ) indicates that it is a total eclipsing binary, which suggests that the determined parameters are reliable. By using 17 new eclipse times together with those collectedmore » from the literature, we found that the general trend of the observed-calculated (O - C) curve shows an upward parabolic variation that corresponds to a long-term increase in the orbital period at a rate of P-dot = +4.1 x 10{sup -8} days yr{sup -1}. The continuous increase may be caused by a mass transfer from the less massive component to the more massive one. This suggests that UZ CMi is in the thermal relaxation oscillation controlled stage of the evolutionary scheme proposed by Qian. UZ CMi will oscillate around a critical mass ratio and the contact configuration cannot be broken. After the upward parabolic change was removed, the (O - C){sub 2} curve of the photoelectric and charge-coupled device data revealed a cyclic variation with a small amplitude of 0.0026 days and a period of 21.1 yr. The cyclic change was analyzed for the light-travel time effect via the presence of an extremely cool stellar companion.« less

Climate related natural hazards management in the vulnerable regions of Uzbekistan - experiences in the frame of projects Climate Risk Management in Uzbekistan (CRM-Uz) and Water in Central Asia (CAWa)

NASA Astrophysics Data System (ADS)

Merkushkin, Alexander; Gafurov, Abror; Agaltseva, Natalya; Pak, Alexander; Mannig, Birgit; Paeth, Heiko; Vorogushyn, Sergiy; Unger-Shayesteh, Katy

2014-05-01

Increased frequency of natural hazards under conditions of observed climate change in Uzbekistan has become challenging concern and shows the need to develop more effective climate risk mechanisms towards improving the security of society and sustainable development. In the framework of presented study, the importance of drought monitoring and methodologies for early warning for such purposes in Uzbekistan are demonstrated. For the conditions of Uzbekistan, droughts are most dangerous climate related natural phenomenon. Therefore, the CRM-Uz Project on Climate Risk Management was established with focus on reducing climate risks, strengthening adaptive capacity for stimulating the development of early warning mechanisms, as well as to build up the basis for long-term investments. This serves to increase resilience to climate impacts in the country. In the frame of the CRM-Uz Project, Drought Early Warning System (DEWS), has been developed and implemented in one of the southern provinces of Uzbekistan (Kashkadarya). The main task of DEWS is to provide population with information on the possibility of upcoming drought season in advance. DEWS is used for the assessment, monitoring, prevention, early warning and decision making in this region. Such early warning system provides the required information to undertake appropriate measures against drought and to mitigate its adverse effects to society. It is clear that during years with expected drought the hydrological forecasts become much more important. Complex mathematical model which simulates of run-off formation as a basis of DEWS provides the seasonal hydrological forecasts that are used to inform all concerned sectors, especially the agricultural sector on water availability during the vegetation period. In the frame of cooperation with German Research Centre for Geosciences (GFZ) within the CAWa Project, the DEWS was extended through implementation of MODSNOW - the operational tool for snow cover monitoring at the Drought Monitoring Centre at UzHydromet. The upgrade of the DEWS withMODSNOW strengthens DEWS's capacity in terms of improvement the hydrological forecasting. Moreover, based on climate scenarios provided within the CAWa project by the University of Würzburg, the regional hydrological model AISHF was used to asses medium and long term water availability in the Kashkadarya River which indicates a reduction of water resources in the selected basin in the future.

New Results on Contact Binary Stars

NASA Astrophysics Data System (ADS)

He, J.; Qian, S.; Zhu, L.; Liu, L.; Liao, W.

2014-08-01

Contact binary star is a kind of close binary with the strongest interaction binary system. Their formations and evolutions are unsolved problems in astrophysics. Since 2000, our groups have observed and studied more than half a hundred of contact binaries. In this report, I will summarize our new results of some contact binary stars (e.g. UZ CMi, GSC 03526-01995, FU Dra, GSC 0763-0572, V524 Mon, MR Com, etc.). They are as follow: (1) We discovered that V524 Mon and MR Com are shallow-contact binaries with their period decreasing; (2) GSC 03526-01995 is middle-contact binary without a period increasing or decreasing continuously; (3) UZ CMi, GSC 0763-0572 and FU Dra are middle-contact binaries with the period increasing continuously; (4) UZ CMi, GSC 03526-01995, FU Dra and V524 Mon show period oscillation which may imply the presence of additional components in these contact binaries.

VizieR Online Data Catalog: BVR light curves of UZ Leo (Lee+, 2018)

NASA Astrophysics Data System (ADS)

Lee, J. W.; Park, J.-H.

2018-04-01

We performed new CCD photometry of UZ Leo during two observing seasons between 2012 February and 2013 April, using a PIXIS: 2048B CCD and a BVR filter set attached to the 61 cm reflector at Sobaeksan Optical Astronomy Observatory (SOAO) in Korea. The CCD chip has 2048x2048pixels and a pixel size of 13.5um, so the field of view of a CCD frame is 17.6'x17.6'. (1 data file).

Vorticity and helicity decompositions and dynamics with real Schur form of the velocity gradient

NASA Astrophysics Data System (ADS)

Zhu, Jian-Zhou

2018-03-01

The real Schur form (RSF) of a generic velocity gradient field ∇u is exploited to expose the structures of flows, in particular, our field decomposition resulting in two vorticities with only mutual linkage as the topological content of the global helicity (accordingly decomposed into two equal parts). The local transformation to the RSF may indicate alternative (co)rotating frame(s) for specifying the objective argument(s) of the constitutive equation. When ∇u is uniformly of RSF in a fixed Cartesian coordinate frame, i.e., ux = ux(x, y) and uy = uy(x, y), but uz = uz(x, y, z), the model, with the decomposed vorticities both frozen-in to u, is for two-component-two-dimensional-coupled-with-one-component-three-dimensional flows in between two-dimensional-three-component (2D3C) and fully three-dimensional-three-component ones and may help curing the pathology in the helical 2D3C absolute equilibrium, making the latter effectively work in more realistic situations.

Accretion as a function of Orbital Phase in Young Close Binaries

NASA Astrophysics Data System (ADS)

Ardila, David R.; Herczeg, G.; Johns-Krull, C. M.; Mathieu, R. D.; Vodniza, A.; Tofflemire, B. M.

2014-01-01

Many planets are known to reside around binaries and the study of young binary systems is crucial to understand their formation. Young ($<10$ Myrs) low-mass binaries are generally surrounded by circumbinary disk with an inner gap. Gas from the disk must cross this gap for accretion to take place and here we present observations of this process as a function of orbital phase. We have obtained time-resolved FUV and NUV spectroscopy (1350 to 3000 A) of DQ Tau and UZ Tau E, using the Cosmic Origins Spectrograph on-board the Hubble Space Telescope. Each target was observed 2 to 4 times per binary orbit, over three or four consecutive orbits. For DQ Tau, we find some evidence that accretion occurs equally into both binary members, while for UZ Tau E this is not the case. H2 emission for DQ Tau most likely originates within the circumbinary gap, while for UZ Tau E no 1000 K gas is detected within the gap, although magnetospheric accretion does take place.

Physical Nature and Orbital Behavior of the Eclipsing System UZ Leonis

NASA Astrophysics Data System (ADS)

Lee, Jae Woo; Park, Jang-Ho

2018-03-01

New CCD photometric observations of UZ Leo were obtained between 2012 February and 2013 April, and on 2017 February. Its physical properties were derived from detailed analyses of our light curves and existing radial velocities. The results indicate that this system is a totally eclipsing A-subtype overcontact binary with both a high fill-out factor of 76% and a third light source contributing 12% light in the B bandpass, 10% in V, and 7% in R. The light residuals between observations and theoretical models are satisfactorily fitted by adopting a magnetic cool spot on the more massive primary star. Including our 12 measurements, a total of 172 eclipse times were used for ephemeris computations. We found that the orbital period of UZ Leo has varied due to a periodic oscillation superposed on an upward parabolic variation. The observed period increase at a rate of +3.49× {10}-7 day yr‑1 can be plausibly explained by some combination of non-conservative mass transfer from the secondary to the primary component and angular momentum loss due to magnetic braking. The period and semi-amplitude of the oscillation are about 139 years and 0.0225 days, respectively, which is interpreted as a light-time effect due to a third component with a mass of {M}3\\sin {i}3=0.30 {M}ȯ . Because the third lights of 7%–12% indicate that the circumbinary object is very overluminous for its mass, it would possibly match a white dwarf, rather than an M-type main sequence.

Therapeutic value of lymph node dissection for right middle lobe non-small-cell lung cancer

PubMed Central

Kuroda, Hiroaki; Mun, Mingyon; Motoi, Noriko; Ishikawa, Yuichi; Nakagawa, Ken; Yatabe, Yasushi; Okumura, Sakae

2016-01-01

Background Superior mediastinal and #11i lymph node (LN) metastases are adverse prognostic factors in patients with middle lobe lung cancer. We aimed to clarify the benefit of thorough lymphadenectomy by LN station or zone in middle lobe non-small-cell lung cancer (NSCLC). Methods Among 295 patients who underwent pulmonary resection and thorough lymphadenectomy for primary right middle lobe (RML) NSCLC at two institutions, we enrolled 68 patients (33 men, 35 women) and retrospectively studied their data. We divided each N1 location (i.e., #10, #11s and #11i) into N1(−)N2(+) and N1(+)N2(+) and divided the #12m location into N1(+)N2(−), N1(−)N2(+) and N1(+)N2(+). Results Interlobar node involvement was rare in pN1 NSCLC when compared with that in other N1 nodes. Lymph node dissection (LND) was beneficial when the hilar zone (HZ)/interlobar zone (IZ) LNs were located at the intermediate point of the upper zones (UZs) and subcarinal zones (SCZs), with the therapeutic benefit at the SCZ being 2.8-fold higher than that at the UZ and 9.7-fold higher than that at the lower zone (LZ). Furthermore, LND evidently had greater therapeutic value for the SCZ than the UZ, which was compatible with skip N2 metastases. Conclusions For middle lobe NSCLC, mediastinal LND should be considered a priority in the SCZ than in the UZ. Moreover, the HZ/IZ is central to unfavourable prognoses in patients with pN2 middle lobe NSCLC. PMID:27162652

Small Hydropower in Latvia and Intellectualization of its Operating Systems / Par Mazo HIDROENERĢĒTIKU LATVIJĀ un TĀS Staciju VADĪBAS SISTĒMAS INTELEKTUALIZĀCIJU

NASA Astrophysics Data System (ADS)

Mahnitko, A.; Gerhards, J.; Linkevics, O.; Varfolomejeva, R.; Umbrasko, I.

2013-12-01

The authors estimate the potential for power generation from water resources of small and medium-sized rivers, which are abundant in Latvia. They propose the algorithm for optimal operation of a small-scale hydropower plant (SHPP) at the chosen optimality criterion in view of the plant's participation in the market. The choice of SHPP optimization algorithm is made based on two mathematical programming methods - dynamic and generalized reduced gradient ones. Approbation of the algorithm is illustrated by an example of optimized SHPP operation. Darbā analizētas tradicionālo un pieejamo vietējo atjaunojamo energoresursu - mazo un vidējo upju hidroresursa izmantošanas iespējas Latvijas enerģētikā. Tiek sniegts faktiskais materiāls šajā jautājumā, kas iegūts, balstoties uz oficiālos avotos publicētiem citu autoru iepriekš veiktajiem pētījumiem. Tiek atzīmēts, ka teritoriju, kas atrodas mazo upju tuvumā un nav ietvertas centralizētās elektroapgādes sistēmā, saimnieciskā apgūšana rada apstākļus patērētāju stimulēšanai izmantot autonomus vietējos energoresursus, ieskaitot hidroenerģiju, izmantojošas mazas jaudas energoiekārtas. Atjaunojamās enerģijas tehnoloģiju un iekārtu pastāvīga attīstība un pilnveidošanās veicinās mazo upju plūsmas izmantošanas elektroenerģijas ražošanas efektivitātes paaugstināšanos. Mūsdienu enerģētikas attīstības koncepcija, kas balstīta uz viedo tīklu (smart grids) izveidi, ļauj paaugstināt mazās hidroenerģētikas darbības efektivitāti, integrējot to elektroenerģētiskajā sistēmā. Mazo hidroelektrostaciju (MHES) darbības vadības sistēmas intelektualizācijas pamatā jābūt kompleksam algoritmam un programmām, kas ļauj tiešsaistes (online) režīmā nodrošināt izdevīgu MHES darbības grafiku (režīmu) maksimālā ienākuma gūšanai, balstoties uz zināmu elektroenerģijas cenas prognozi attiecīgajam laika periodam (diennaktij). MHES darbības optimizācijas algoritma, kas pēc būtības ir tās vadības pamats, izstrāde tiek veikta, balstoties uz klasiskās matemātiskas programmēšanas metodes - dinamiskās programmēšanas metodi un vispārināto reducēto gradienta metodi. Izstrādājot programmu kodus, kas realizē autonomā režīmā strādājošas MHES optimizācijas algoritmu, nepieciešams izmantot speciālas aprēķinu procedūras, kas ir adaptīvas pret konkrētiem MHES ūdens spiediena ierobežojumiem. Algoritma aprobācija veikta uz konkrētas MHES režīma optimizācijas piemēra.

Land surface temperature as an indicator of the unsaturated zone thickness: A remote sensing approach in the Atacama Desert.

PubMed

Urqueta, Harry; Jódar, Jorge; Herrera, Christian; Wilke, Hans-G; Medina, Agustín; Urrutia, Javier; Custodio, Emilio; Rodríguez, Jazna

2018-01-15

Land surface temperature (LST) seems to be related to the temperature of shallow aquifers and the unsaturated zone thickness (∆Z uz ). That relationship is valid when the study area fulfils certain characteristics: a) there should be no downward moisture fluxes in an unsaturated zone, b) the soil composition in terms of both, the different horizon materials and their corresponding thermal and hydraulic properties, must be as homogeneous and isotropic as possible, c) flat and regular topography, and d) steady state groundwater temperature with a spatially homogeneous temperature distribution. A night time Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image and temperature field measurements are used to test the validity of the relationship between LST and ∆Z uz at the Pampa del Tamarugal, which is located in the Atacama Desert (Chile) and meets the above required conditions. The results indicate that there is a relation between the land surface temperature and the unsaturated zone thickness in the study area. Moreover, the field measurements of soil temperature indicate that shallow aquifers dampen both the daily and the seasonal amplitude of the temperature oscillation generated by the local climate conditions. Despite empirically observing the relationship between the LST and ∆Z uz in the study zone, such a relationship cannot be applied to directly estimate ∆Z uz using temperatures from nighttime thermal satellite images. To this end, it is necessary to consider the soil thermal properties, the soil surface roughness and the unseen water and moisture fluxes (e.g., capillarity and evaporation) that typically occur in the subsurface. Copyright © 2017 Elsevier B.V. All rights reserved.

Iridoplasty of fixed-dilated pupil (Urrets-Zavalia syndrome) after deep anterior lamellar keratoplasty

PubMed Central

Ntora, Efthalia; Ziakas, Nikolaos

2017-01-01

A 38-year-old woman with advanced keratoconus initially developed Urrets-Zavalia Syndrome (UZS) in the left eye after deep anterior lamellar keratoplasty. During the uneventful surgery, a 7-mm-wide pupil unresponsive to light was noticed. On the first postoperative day, intraocular pressure (IOP) was elevated up to 45 mmHg with shallow anterior chamber (AC). A peripheral iridotomy in 2 o’clock position was conducted and a fixed combination of brinzolamide 1% and timolol 0.5% was administered topically. In the subsequent postoperative period, IOP was successfully reduced, but the patient reported severe photophobia, glare, and decreased vision. Twelve months after surgery, her best-corrected visual acuity (BCVA) was 20/200, the fixed-dilated pupil persisted, iris was atrophic, and lens opacities were detected. She was submitted for phacoemulsification cataract surgery combined with iridoplasty using the closed chamber slipping suture technique. Three months after surgery, her BCVA was 20/25, pupil diameter remained stable at 4 mm, and glare symptoms were significantly reduced. A very adequate cosmetic outcome was also achieved. Iridoplasty in postkeratoplasty patient with unilateral UZS was effective in improving patient's visual function disability and restoring residual anisocoria. This technique can be applied as a single procedure or combined with another one for the management of UZS. PMID:29118500

Anti-Uz found in mother's serum and child's eluate.

PubMed

Read, S M; Taylor, M M; Reid, M E; Popovsky, M A

1993-01-01

A saline-reactive antibody, anti-Uz, that reacted stronger with S+ than with S- red blood cells (RBCs) and failed to react with U- or ficin-treated RBCs has been previously reported. We describe an antibody of similar specificity in the postpartum serum of an untransfused woman and the eluate from her fourth child's cord RBCs. The mother's RBCs typed S-s+U+, He+(weak), and appeared to have normal glycophorin A and B content, as deter- mined by immunoblotting. The direct antiglobulin test (DAT) and the autocontrol were negative. Her serum reacted stronger with S + RBCs only in the antiglobulin phase, and failed to react with U- or ficin-treated RBCs. The antibody was adsorbed completely by S-s+U+ RBCs, proving that anti-S was not present. Monocyte monolayer assay results with S+s-U+ and S-s+U+ RBCs indicated that transfusion of incompatible blood would not result in significant hemolysis. The child's cord RBCs typed S-s+. The DAT was 3+ with anti-IgG, and an eluate prepared from these RBCs had the same reactivity as the maternal serum. The child showed no clinical signs of hemolytic disease of the newborn. In contrast to previous reports, these results suggest an immune form of anti-Uz.

Insights into controls on hexavalent chromium in groundwater provided by environmental tracers, Sacramento Valley, California, USA

USGS Publications Warehouse

Manning, Andrew H.; Mills, Christopher T.; Morrison, Jean M.; Ball, Lyndsay B.

2015-01-01

Environmental tracers are useful for determining groundwater age and recharge source, yet their application in studies of geogenic Cr(VI) in groundwater has been limited. Environmental tracer data from 166 wells located in the Sacramento Valley, northern California, were interpreted and compared to Cr concentrations to determine the origin and age of groundwater with elevated Cr(VI), and better understand where Cr(VI) becomes mobilized and how it evolves along flowpaths. In addition to major ion and trace element concentrations, the dataset includes δ18O, δ2H, 3H concentration, 14C activity (of dissolved inorganic C), δ13C, 3He/4He ratio, and noble gas concentrations (He, Ne, Ar, Kr, Xe). Noble gas recharge temperatures (NGTs) were computed, and age-related tracers were interpreted in combination to constrain the age distribution in samples and sort them into six different age categories spanning from <60 yr old to >10,000 yr old. Nearly all measured Cr is in the form of Cr(IV). Concentrations range from <1 to 46 μg L−1, with 10% exceeding the state of California’s Cr(VI) maximum contaminant level of 10 μg L−1. Two groups with elevated Cr(VI) (⩾5 μg L−1) were identified. Group 1 samples are from the southern part of the valley and contain modern (<60 yr old) water, have elevated NO3− concentrations (>3 mg L−1), and commonly have δ18O values enriched relative to local precipitation. These samples likely contain irrigation water and are elevated due to accelerated mobilization of Cr(VI) in the unsaturated zone (UZ) in irrigated areas. Group 2 samples are from throughout the valley and typically contain water 1000–10,000 yr old, have δ18O values consistent with local precipitation, and have unexpectedly warm NGTs. Chromium(VI) concentrations in Group 2 samples may be elevated for multiple reasons, but the hypothesis most consistent with all available data (notably, the warm NGTs) is a relatively long UZ residence time due to recharge through a deep UZ near the margin of the basin. A possible explanation for why Cr(VI) may be primarily mobilized in the UZ rather than farther along flowpaths in the oxic portion of the saturated zone is more dynamic cycling of Mn in the UZ due to transient moisture and redox conditions.

Chemistry of unsaturated zone gases sampled in open boreholes at the crest of Yucca Mountain, Nevada: Data and basic concepts of chemical and physical processes in the mountain

USGS Publications Warehouse

Thorstenson, Donald C.; Weeks, Edwin P.; Haas, Herbert; Busenberg, Eurybiades; Plummer, Niel; Peters, Charles A.

1998-01-01

Boreholes open to the unsaturated zone at the crest of Yucca Mountain, Nevada, were variously sampled for CO2 (including 13C and 14C), CH4, N2, O2, Ar, CFC-11, CFC-12, and CFC-113 from 1986 to 1993. Air enters the mountain in outcrops, principally on the eastern slope, is enriched in CO2by mixing with soil gas, and is advected to the mountain crest, where it returns to the atmosphere. The CFC data indicate that travel times of the advecting gas in the shallow Tiva Canyon hydrogeologic unit are ≤5 years. The 14C activities are postbomb to depths of 100 m, indicating little retardation of 14CO2 in the shallow flow systems. The 14C activities from 168 to 404 m in the Topopah Spring hydrogeologic unit are 85–90 pMC at borehole USW-UZ6. The CFC data show that the drilling of USW-UZ6 in 1984 has altered the natural system by providing a conduit through the Paintbrush Nonwelded unit, allowing flow from Topopah Spring outcrops in Solitario Canyon on the west to USW-UZ6, upward in the borehole through the Paintbrush, to the shallow Tiva Canyon flow systems, and out of the mountain.

Geologic Framework Model Analysis Model Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. Clayton

2000-12-19

The purpose of this report is to document the Geologic Framework Model (GFM), Version 3.1 (GFM3.1) with regard to data input, modeling methods, assumptions, uncertainties, limitations, and validation of the model results, qualification status of the model, and the differences between Version 3.1 and previous versions. The GFM represents a three-dimensional interpretation of the stratigraphy and structural features of the location of the potential Yucca Mountain radioactive waste repository. The GFM encompasses an area of 65 square miles (170 square kilometers) and a volume of 185 cubic miles (771 cubic kilometers). The boundaries of the GFM were chosen to encompassmore » the most widely distributed set of exploratory boreholes (the Water Table or WT series) and to provide a geologic framework over the area of interest for hydrologic flow and radionuclide transport modeling through the unsaturated zone (UZ). The depth of the model is constrained by the inferred depth of the Tertiary-Paleozoic unconformity. The GFM was constructed from geologic map and borehole data. Additional information from measured stratigraphy sections, gravity profiles, and seismic profiles was also considered. This interim change notice (ICN) was prepared in accordance with the Technical Work Plan for the Integrated Site Model Process Model Report Revision 01 (CRWMS M&O 2000). The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The GFM is one component of the Integrated Site Model (ISM) (Figure l), which has been developed to provide a consistent volumetric portrayal of the rock layers, rock properties, and mineralogy of the Yucca Mountain site. The ISM consists of three components: (1) Geologic Framework Model (GFM); (2) Rock Properties Model (RPM); and (3) Mineralogic Model (MM). The ISM merges the detailed project stratigraphy into model stratigraphic units that are most useful for the primary downstream models and the repository design. These downstream models include the hydrologic flow models and the radionuclide transport models. All the models and the repository design, in turn, will be incorporated into the Total System Performance Assessment (TSPA) of the potential radioactive waste repository block and vicinity to determine the suitability of Yucca Mountain as a host for the repository. The interrelationship of the three components of the ISM and their interface with downstream uses are illustrated in Figure 2.« less

Targeting bed nucleus of the stria terminalis for severe obsessive-compulsive disorder: more unexpected lead placement in obsessive-compulsive disorder than in surgery for movement disorders.

PubMed

Nuttin, Bart; Gielen, Frans; van Kuyck, Kris; Wu, Hemmings; Luyten, Laura; Welkenhuysen, Marleen; Brionne, Thomas C; Gabriëls, Loes

2013-01-01

In preparation for a multicenter study, a protocol was written on how to perform surgical targeting of the bed nucleus of the stria terminalis, based on the lead implantation experience in patients with treatment-refractory obsessive-compulsive disorder (OCD) at the Universitaire Ziekenhuizen Leuven (UZ Leuven). When analyzing the postoperative images, we were struck by the fact that the difference between the postoperative position of the leads and the planned position seemed larger than expected. The precision of targeting in four patients with severe OCD who received bilateral model 3391 leads (Medtronic) was compared with the precision of targeting in the last seven patients who underwent surgery at UZ Leuven for movement disorders (four with Parkinson disease and three with essential tremor; all received bilateral leads). Because the leads implanted in six of the seven patients with movement disorders were model 3387 leads (Medtronic), targeting precision was also analyzed in four patients with OCD in whom model 3387 leads were implanted in the same target as the other patients with OCD. In the patients with OCD, every implanted lead deviated at least 1.3 mm from its intended position in at least one of three directions (lateral, anteroposterior, and depth), whereas in the patients with movement disorders, the maximal deviation of any of all implanted leads was 1.3 mm. The deviations in lead placement were comparable in patients with OCD who received a model 3387 implant and patients who received a model 3391 implant. In the patients with OCD, all leads were implanted more posteriorly than planned. The cause of the posterior deviation could not be determined with certainty. The most likely cause was an increased mechanical resistance of the brain tissue along the trajectory when following the targeting protocol compared with the trajectories classically used for subthalamic nucleus or ventral intermediate nucleus of the thalamus stimulation. Copyright © 2013 Elsevier Inc. All rights reserved.

Fixed mydriatic pupil associated with an intraocular pressure rise as a complication of the implant of a Phakic Refractive Lens (PRL).

PubMed

Pérez-Cambrodí, Rafael José; Piñero-Llorens, David Pablo; Ruiz-Fortes, Juan Pedro; Blanes-Mompó, Francisco Javier; Cerviño-Expósito, Alejandro

2014-07-01

We describe a case report of a patient that was implanted with a posterior chamber phakic intraocular lens (Phakic Refractive Lens, PRL) for the correction of moderate myopia and who developed postoperatively a fixed mydriasis compatible with an Urrets-Zavalia Syndrome (UZS). Specifically, a sudden acute increase of IOP in the left eye was observed in the immediate postoperative period. After IOP stabilization, the refractive result was good, but a fixed and mydriatic pupil appeared. This condition led the patient to experience visual discomfort, halos, and glare associated with high levels of higher-order aberrations in spite of the good visual result. A tinted-contact lens was fitted in order to minimize those symptoms. The UZS should be considered as a possible complication after implantation of posterior chamber phakic intraocular lenses.

Carbon isotopic data from test hole USW UZ-1, Yucca Mountain, Nevada

USGS Publications Warehouse

Yang, In C.; Peters, C.A.; Thorstenson, D.C.

1993-01-01

Rock-CO2-gas analyses in test hole USW UZ-1 at Yucca Mountain indicate that gas movement in the unsaturated zone is likely through a dry-fracture system with little porewater or caliche-calcite interaction. This is because near-surface ??13C values are of biogenic origin and have changed little throughout the total depth. Post-bomb 14C activity is observed to the depth of about 12 m. An abrupt change in plotted 14C/depth slope is seen at 61 m. The less steep upper segment corresponds to the zone with greater porosity and moisture content, and consequently more tortuosity, with an estimated traveltime of 1.27 cm/yr; the steeper sloped zone corresponding to the lower segment has smaller porosity and moisture content but larger fracture density for gas transport, with an estimated traveltime of 3.26 cm/yr.

The saturated zone at Yucca Mountain: An overview of the characterization and assessment of the saturated zone as a barrier to potential radionuclide migration

USGS Publications Warehouse

Eddebbarh, A.-A.; Zyvoloski, G.A.; Robinson, B.A.; Kwicklis, E.M.; Reimus, P.W.; Arnold, B.W.; Corbet, T.; Kuzio, S.P.; Faunt, C.

2003-01-01

The US Department of Energy is pursuing Yucca Mountain, Nevada, for the development of a geologic repository for the disposal of spent nuclear fuel and high-level radioactive waste, if the repository is able to meet applicable radiation protection standards established by the US Nuclear Regulatory Commission and the US Environmental Protection Agency (EPA). Effective performance of such a repository would rely on a number of natural and engineered barriers to isolate radioactive waste from the accessible environment. Groundwater beneath Yucca Mountain is the primary medium through which most radionuclides might move away from the potential repository. The saturated zone (SZ) system is expected to act as a natural barrier to this possible movement of radionuclides both by delaying their transport and by reducing their concentration before they reach the accessible environment. Information obtained from Yucca Mountain Site Characterization Project activities is used to estimate groundwater flow rates through the site-scale SZ flow and transport model area and to constrain general conceptual models of groundwater flow in the site-scale area. The site-scale conceptual model is a synthesis of what is known about flow and transport processes at the scale required for total system performance assessment of the site. This knowledge builds on and is consistent with knowledge that has accumulated at the regional scale but is more detailed because more data are available at the site-scale level. The mathematical basis of the site-scale model and the associated numerical approaches are designed to assist in quantifying the uncertainty in the permeability of rocks in the geologic framework model and to represent accurately the flow and transport processes included in the site-scale conceptual model. Confidence in the results of the mathematical model was obtained by comparing calculated to observed hydraulic heads, estimated to measured permeabilities, and lateral flow rates calculated by the site-scale model to those calculated by the regional-scale flow model. In addition, it was confirmed that the flow paths leaving the region of the potential repository are consistent with those inferred from gradients of measured head and those independently inferred from water-chemistry data. The general approach of the site-scale SZ flow and transport model analysis is to calculate unit breakthrough curves for radionuclides at the interface between the SZ and the biosphere using the three-dimensional site-scale SZ flow and transport model. Uncertainties are explicitly incorporated into the site-scale SZ flow and transport abstractions through key parameters and conceptual models. ?? 2002 Elsevier Science B.V. All rights reserved.

Geohydrologic data from test hole USW UZ-7, Yucca Mountain area, Nye County, Nevada

USGS Publications Warehouse

Kume, Jack; Hammermeister, D.P.

1990-01-01

This report contains a description of the methods used in drilling and coring of the test-hole USW UZ-7, a description of the methods used in collecting, handling, and testing of test-hole samples; Lithologic information from the test hole; and water-content, water-potential, bulk-density, grain-density, porosity, and tritium data for the test hole. Test-hole USW UZ-7 was drilled and cored to a total depth of 62.94 m. The drilling was done using air as a drilling fluid to minimize disturbance to the water content of cores, drill-bit cuttings, and borehole wall-rock. Beginning at the land surface, the unsaturated-zone rock that was penetrated consisted of alluvium; welded and partially to nonwelded ash-flow tuff; bedded and reworked ash-fall tuff; nonwelded ash-flow tuff; and welded ash-flow tuff. Values of gravimetric water content and water potential of alluvium were intermediate between the extreme values in welded and nonwelded units of tuff. Gravimetric water content was largest in bedded and nonwelded ash-fall tuffs and was smallest in welded ash-flow tuff. Values of water potential were more negative in densely welded ash-flow tuffs and were less negative in bedded and nonwelded ash-fall tuffs. Bulk density was largest in densely welded ash-flow tuffs and smallest in nonwelded and bedded ash-fall tuffs. Grain density was uniform but was slightly larger in nonwelded and bedded ash-fall tuffs than in welded ash-flow tuffs. Porosity trends were opposite to bulk-density trends. Tritium content in alluvium was smallest near the alluvium-bedrock contact, markedly increased in the middle of the deposit, and decreased in the near-surface zone of the deposit. (Author 's abstract)

On the Periodic Solutions of the Five-Dimensional Lorenz Equation Modeling Coupled Rosby Waves and Gravity Waves

NASA Astrophysics Data System (ADS)

Carvalho, Tiago; Llibre, Jaume

2017-06-01

Lorenz studied the coupled Rosby waves and gravity waves using the differential system U˙ = -VW + bVZ,V˙ = UW - bUZ,Ẇ = -UV,Ẋ = -Z,Ż = bUV + X. This system has the two first integrals H1 = U2 + V2,H 2 = V2 + W2 + X2 + Z2. Our main result shows that in each invariant set {H1 = h1 > 0}∩{H2 = h2 > 0} there are at least four (resp., 2) periodic solutions of the differential system with b≠0 and h2 > h1 (resp., h2 < h1).

Drilling, logging, and testing information from borehole UE-25 UZ{number_sign}16, Yucca Mountain, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thamir, F.; Thordarson, W.; Kume, J.

Borehole UE-25 UZ{number_sign}16 is the first of two boreholes that may be used to determine the subsurface structure at Yucca Mountain by using vertical seismic profiling. This report contains information collected while this borehole was being drilled, logged, and tested from May 27, 1992, to April 22, 1994. It does not contain the vertical seismic profiling data. This report is intended to be used as: (1) a reference for drilling similar boreholes in the same area, (2) a data source on this borehole, and (3) a reference for other information that is available from this borehole. The reference information includesmore » drilling chronology, equipment, parameters, coring methods, penetration rates, completion information, drilling problems, and corrective actions. The data sources include lithology, fracture logs, a list of available borehole logs, and depths at which water was recorded. Other information is listed in an appendix that includes studies done after April 22, 1994.« less

Physical and Technical Energy Problems: Testing of the Prototype for State Estimation of Large-Scale Power Systems / Lielo Energosistēmu Stāvokļa Novērtēšanas Prototipa Testēšana

NASA Astrophysics Data System (ADS)

Kochukov, O.; Briņķis, K.; Mutule, A.

2013-08-01

The paper describes the algorithm for distributed state estimation (SE) and is focused on its testing and validation. For this purpose, different events in the modeled power system of the 330-750 kV electrical ring Latvia - Lithuania - Belarus - Smolensk - Moscow - St. Petersburg - Estonia - Latvia were considered. The methods for testing the Inter-TSO SE prototype and dynamic network monitoring & modeling are based on comparison of the available SCADA data about real events with those of SE calculation. In total, four operational states were studied, including initial, accident and two post-accident operational states Rakstā tiek aprakstīti, testēti un novērtēti izkliedēta stāvokļa novērtēšanas algoritmi. Testēšanas nolūkos tika izmantoti dažādi 330-750 kV elektriskā loka Latvija - Lietuva - Baltkrievija - Smoļenska - Maskava - Pēterburga - Igaunija - Latvija modelēti scenāriji. Prototipa testēšanas metodoloģija balstīta uz pieejamo SCADA datu salīdzināšanu ar stāvokļa novērtēšanas prototipa aprēķina rezultātiem. Kopumā apskatīti sākotnējais, avārijas un divi pēcavārijas režīmi

Identity of Innovative Multifunctional Material Manufacturing Business in Latvia / Inovatīvu Daudzfunkcionālo Materiālu Ražotāju Identitāte Latvijā

NASA Astrophysics Data System (ADS)

Geipele, I.; Staube, T.; Ciemleja, G.; Zeltins, N.; Ekmanis, Yu.

2015-08-01

The publication comprises the results from the practical scientific investigation to define the profile and distinctions of the Latvian innovative multifunctional material manufacturing industry. The research is carried out by a holistic approach, including expert interviews, qualitative analysis of the official register data, practical survey, and financial data analysis. The paper seeks to give the detailed data on a technological profile of the mentioned representative companies, if there is a synergy or tough competition in the Latvian market. The current research is topical, because it is unique and does not have analogues in Latvia, and the research is timely due to correspondence with recently stated Research and Innovation Strategies for Smart Specialisation in Latvia. The main findings are associated with recognition of the factors that make impact on commercialisation of the finished goods, obtained financial results and planned directions of development of the respondent companies. Publikācija sniedz veiktā zinātniski praktiskā pētījuma rezultātus, kura ietvaros tika noteikts Latvijas inovatīvu daudzfunkcionālo materiālu ražotāju darbības profils un identitāte. Pētījumā tika izmantota kompleksās analīzes metode, kas ietvēra ekspertu intervijas, uzņēmumu oficiāli reģistrēto datu kvalitatīvo analīzi, zinātniski praktisko aptauju, kā arī pētāmo uzņēmumu finanšu darbības rezultātu analīzi. Zinātniskais darbs sniedz izsmeļošu informāciju par mērķa uzņēmumu tehnoloģisko profilu un pēta, vai Latvijas mērķa ražošanas nozarē ir sinerģijas vai sīvās konkurences pazīmes. Šim zinātniskajam pētījumam ir noteikta aktualitāte saskaņā ar tā unikalitāti Latvijas valsts mērogā un atbilstība Viedās specializācijas stratēģijai. Pētījuma galvenie secinājumi ir saistīti ar uzņēmumu produkcijas komercializācijas ietekmējošo faktoru apzināšanu, sasniegtajiem finansiālajiem rezultātiem un plānotajiem attīstības virzieniem.

Chlorine-36 data at Yucca Mountain: Statistical tests of conceptual models for unsaturated-zone flow

USGS Publications Warehouse

Campbell, K.; Wolfsberg, A.; Fabryka-Martin, J.; Sweetkind, D.

2003-01-01

An extensive set of chlorine-36 (36Cl) data has been collected in the Exploratory Studies Facility (ESF), an 8-km-long tunnel at Yucca Mountain, Nevada, for the purpose of developing and testing conceptual models of flow and transport in the unsaturated zone (UZ) at this site. At several locations, the measured values of 36Cl/Cl ratios for salts leached from rock samples are high enough to provide strong evidence that at least a small component of bomb-pulse 36Cl, fallout from atmospheric testing of nuclear devices in the 1950s and 1960s, was measured, implying that some fraction of the water traveled from the ground surface through 200-300 m of unsaturated rock to the level of the ESF during the last 50 years. These data are analyzed here using a formal statistical approach based on log-linear models to evaluate alternative conceptual models for the distribution of such fast flow paths. The most significant determinant of the presence of bomb-pulse 36Cl in a sample from the welded Topopah Spring unit (TSw) is the structural setting from which the sample was collected. Our analysis generally supports the conceptual model that a fault that cuts through the nonwelded Paintbrush tuff unit (PTn) that overlies the TSw is required in order for bomb-pulse 36Cl to be transmitted to the sample depth in less than 50 years. Away from PTn-cutting faults, the ages of water samples at the ESF appear to be a strong function of the thickness of the nonwelded tuff between the ground surface and the ESF, due to slow matrix flow in that unit. ?? 2002 Elsevier Science B.V. All rights reserved.

Rapid Identification of Vector-Borne Flaviviruses by Mass Spectrometry

DTIC Science & Technology

2010-01-01

FE Mass 93 Human/1993 NR Karshi virus KV UZ-2247 Ticks/Uzbekistan/? NR Kyasanur Forest disease virus KFDV W371 Human/India/1957 AF013385 Langat LGTV...acterized samples that have been tested on other diagnostic plat- forms, the detection of viruses such as Tembusu and Langat viruses demonstrates the

VizieR Online Data Catalog: UBV light curves of DQ Tau and UZ Tau E (Ardila+, 2015)

NASA Astrophysics Data System (ADS)

Ardila, D. R.; Jonhs-Krull, C.; Herczeg, G. J.; Mathieu, R. D.; Quijano-Vodniza, A.

2016-01-01

DQ Tau was observed with HST/COS four times per binary orbit, during three consecutive binary orbits, at phases ~0, ~0.2, ~0.5, and ~0.7 (in 2011 Feb, Mar). The original experimental design called for observations of UZ Tau E with the same cadence. However, the NUV observations at phase ~0.7 in the second orbit and both the FUV and NUV observations at phase ~0 in the third orbit failed. They were replaced by observations at phases ~0 and ~0.5 in a fourth binary orbit (in 2011 Feb, Mar, Apr). We obtained contemporaneous ground-based UBV photometry with the 14" telescope from the University of Narino Observatory, optical spectroscopy with the Sandiford Echelle Spectrometer on the 2.1m Otto Struve Telescope at McDonald Observatory, near-infrared spectroscopy with the CSHELL spectrograph on the NASA Infrared Telescope Facility, and near-infrared spectroscopy with GNIRS instrument on Gemini North. In this paper we focus on the U-band photometry only. UBV observations were obtained before and during the HST campaign. See table 3. (1 data file).

A comparison of hydrologic models for ecological flows and water availability

USGS Publications Warehouse

Caldwell, Peter V; Kennen, Jonathan G.; Sun, Ge; Kiang, Julie E.; Butcher, John B; Eddy, Michelle C; Hay, Lauren E.; LaFontaine, Jacob H.; Hain, Ernie F.; Nelson, Stacy C; McNulty, Steve G

2015-01-01

Robust hydrologic models are needed to help manage water resources for healthy aquatic ecosystems and reliable water supplies for people, but there is a lack of comprehensive model comparison studies that quantify differences in streamflow predictions among model applications developed to answer management questions. We assessed differences in daily streamflow predictions by four fine-scale models and two regional-scale monthly time step models by comparing model fit statistics and bias in ecologically relevant flow statistics (ERFSs) at five sites in the Southeastern USA. Models were calibrated to different extents, including uncalibrated (level A), calibrated to a downstream site (level B), calibrated specifically for the site (level C) and calibrated for the site with adjusted precipitation and temperature inputs (level D). All models generally captured the magnitude and variability of observed streamflows at the five study sites, and increasing level of model calibration generally improved performance. All models had at least 1 of 14 ERFSs falling outside a +/−30% range of hydrologic uncertainty at every site, and ERFSs related to low flows were frequently over-predicted. Our results do not indicate that any specific hydrologic model is superior to the others evaluated at all sites and for all measures of model performance. Instead, we provide evidence that (1) model performance is as likely to be related to calibration strategy as it is to model structure and (2) simple, regional-scale models have comparable performance to the more complex, fine-scale models at a monthly time step.

Discovery and structure determination of the orphan enzyme isoxanthopterin deaminase .

PubMed

Hall, Richard S; Agarwal, Rakhi; Hitchcock, Daniel; Sauder, J Michael; Burley, Stephen K; Swaminathan, Subramanyam; Raushel, Frank M

2010-05-25

Two previously uncharacterized proteins have been identified that efficiently catalyze the deamination of isoxanthopterin and pterin 6-carboxylate. The genes encoding these two enzymes, NYSGXRC-9339a ( gi|44585104 ) and NYSGXRC-9236b ( gi|44611670 ), were first identified from DNA isolated from the Sargasso Sea as part of the Global Ocean Sampling Project. The genes were synthesized, and the proteins were subsequently expressed and purified. The X-ray structure of Sgx9339a was determined at 2.7 A resolution (Protein Data Bank entry 2PAJ ). This protein folds as a distorted (beta/alpha)(8) barrel and contains a single zinc ion in the active site. These enzymes are members of the amidohydrolase superfamily and belong to cog0402 within the clusters of orthologous groups (COG). Enzymes in cog0402 have previously been shown to catalyze the deamination of guanine, cytosine, S-adenosylhomocysteine, and 8-oxoguanine. A small compound library of pteridines, purines, and pyrimidines was used to probe catalytic activity. The only substrates identified in this search were isoxanthopterin and pterin 6-carboxylate. The kinetic constants for the deamination of isoxanthopterin with Sgx9339a were determined to be 1.0 s(-1), 8.0 muM, and 1.3 x 10(5) M(-1) s(-1) (k(cat), K(m), and k(cat)/K(m), respectively). The active site of Sgx9339a most closely resembles the active site for 8-oxoguanine deaminase (Protein Data Bank entry 2UZ9 ). A model for substrate recognition of isoxanthopterin by Sgx9339a was proposed on the basis of the binding of guanine and xanthine in the active site of guanine deaminase. Residues critical for substrate binding appear to be conserved glutamine and tyrosine residues that form hydrogen bonds with the carbonyl oxygen at C4, a conserved threonine residue that forms hydrogen bonds with N5, and another conserved threonine residue that forms hydrogen bonds with the carbonyl group at C7. These conserved active site residues were used to identify 24 other genes which are predicted to deaminate isoxanthopterin.

Post Audit of a Field Scale Reactive Transport Model of Uranium at a Former Mill Site

NASA Astrophysics Data System (ADS)

Curtis, G. P.

2015-12-01

Reactive transport of hexavalent uranium (U(VI)) in a shallow alluvial aquifer at a former uranium mill tailings site near Naturita CO has been monitored for nearly 30 years by the US Department of Energy and the US Geological Survey. Groundwater at the site has high concentrations of chloride, alkalinity and U(VI) as a owing to ore processing at the site from 1941 to 1974. We previously calibrated a multicomponent reactive transport model to data collected at the site from 1986 to 2001. A two dimensional nonreactive transport model used a uniform hydraulic conductivity which was estimated from observed chloride concentrations and tritium helium age dates. A reactive transport model for the 2km long site was developed by including an equilibrium U(VI) surface complexation model calibrated to laboratory data and calcite equilibrium. The calibrated model reproduced both nonreactive tracers as well as the observed U(VI), pH and alkalinity. Forward simulations for the period 2002-2015 conducted with the calibrated model predict significantly faster natural attenuation of U(VI) concentrations than has been observed by the persistent high U(VI) concentrations at the site. Alternative modeling approaches are being evaluating evaluated using recent data to determine if the persistence can be explained by multirate mass transfer models developed from experimental observations at the column scale(~0.2m), the laboratory tank scale (~2m), the field tracer test scale (~1-4m) or geophysical observation scale (~1-5m). Results of this comparison should provide insight into the persistence of U(VI) plumes and improved management options.

A simplified gross primary production and evapotranspiration model for boreal coniferous forests - is a generic calibration sufficient?

NASA Astrophysics Data System (ADS)

Minunno, F.; Peltoniemi, M.; Launiainen, S.; Aurela, M.; Lindroth, A.; Lohila, A.; Mammarella, I.; Minkkinen, K.; Mäkelä, A.

2015-07-01

The problem of model complexity has been lively debated in environmental sciences as well as in the forest modelling community. Simple models are less input demanding and their calibration involves a lower number of parameters, but they might be suitable only at local scale. In this work we calibrated a simplified ecosystem process model (PRELES) to data from multiple sites and we tested if PRELES can be used at regional scale to estimate the carbon and water fluxes of Boreal conifer forests. We compared a multi-site (M-S) with site-specific (S-S) calibrations. Model calibrations and evaluations were carried out by the means of the Bayesian method; Bayesian calibration (BC) and Bayesian model comparison (BMC) were used to quantify the uncertainty in model parameters and model structure. To evaluate model performances BMC results were combined with more classical analysis of model-data mismatch (M-DM). Evapotranspiration (ET) and gross primary production (GPP) measurements collected in 10 sites of Finland and Sweden were used in the study. Calibration results showed that similar estimates were obtained for the parameters at which model outputs are most sensitive. No significant differences were encountered in the predictions of the multi-site and site-specific versions of PRELES with exception of a site with agricultural history (Alkkia). Although PRELES predicted GPP better than evapotranspiration, we concluded that the model can be reliably used at regional scale to simulate carbon and water fluxes of Boreal forests. Our analyses underlined also the importance of using long and carefully collected flux datasets in model calibration. In fact, even a single site can provide model calibrations that can be applied at a wider spatial scale, since it covers a wide range of variability in climatic conditions.

Modeling Continuous-Time Random Processes in Digital Computer Simulations of Physical Systems

DTIC Science & Technology

1986-08-27

hf) + BD1QD1B31 + BD2QD2B62 + BD3QD3BZ3 + BD4QD4BZ4 (51) where ODk = E[NDk-_•k] for k = 1 to 4. Note that PD(ti+l) has four BDiQDiBZi terms, one from...3 , collecting terms, and rearrang- ing equation (95), results in (aUz 3 + a 2 z 2 + a3z + ag4)hBV(z)Xlz) , (96) z 4 - alhAz 3 - (1 + a2 hA)z 2 - a 3...approximate the Taylor series form of I(h,I)? To answer this question, expand equation (1ll) in a series form , collect terms and compare it to 1(hI) . EhA

Spatial Interpretation of Tower, Chamber and Modelled Terrestrial Fluxes in a Tropical Forest Plantation

NASA Astrophysics Data System (ADS)

Whidden, E.; Roulet, N.

2003-04-01

Interpretation of a site average terrestrial flux may be complicated in the presence of inhomogeneities. Inhomogeneity may invalidate the basic assumptions of aerodynamic flux measurement. Chamber measurement may miss or misinterpret important temporal or spatial anomalies. Models may smooth over important nonlinearities depending on the scale of application. Although inhomogeneity is usually seen as a design problem, many sites have spatial variance that may have a large impact on net flux, and in many cases a large homogeneous surface is unrealistic. The sensitivity and validity of a site average flux are investigated in the presence of an inhomogeneous site. Directional differences are used to evaluate the validity of aerodynamic methods and the computation of a site average tower flux. Empirical and modelling methods are used to interpret the spatial controls on flux. An ecosystem model, Ecosys, is used to assess spatial length scales appropriate to the ecophysiologic controls. A diffusion model is used to compare tower, chamber, and model data, by spatially weighting contributions within the tower footprint. Diffusion model weighting is also used to improve tower flux estimates by producing footprint averaged ecological parameters (soil moisture, soil temperature, etc.). Although uncertainty remains in the validity of measurement methods and the accuracy of diffusion models, a detailed spatial interpretation is required at an inhomogeneous site. Flux estimation between methods improves with spatial interpretation, showing the importance to an estimation of a site average flux. Small-scale temporal and spatial anomalies may be relatively unimportant to overall flux, but accounting for medium-scale differences in ecophysiological controls is necessary. A combination of measurements and modelling can be used to define the appropriate time and length scales of significant non-linearity due to inhomogeneity.

The General Ensemble Biogeochemical Modeling System (GEMS) and its applications to agricultural systems in the United States: Chapter 18

USGS Publications Warehouse

Liu, Shuguang; Tan, Zhengxi; Chen, Mingshi; Liu, Jinxun; Wein, Anne; Li, Zhengpeng; Huang, Shengli; Oeding, Jennifer; Young, Claudia; Verma, Shashi B.; Suyker, Andrew E.; Faulkner, Stephen P.

2012-01-01

The General Ensemble Biogeochemical Modeling System (GEMS) was es in individual models, it uses multiple site-scale biogeochemical models to perform model simulations. Second, it adopts Monte Carlo ensemble simulations of each simulation unit (one site/pixel or group of sites/pixels with similar biophysical conditions) to incorporate uncertainties and variability (as measured by variances and covariance) of input variables into model simulations. In this chapter, we illustrate the applications of GEMS at the site and regional scales with an emphasis on incorporating agricultural practices. Challenges in modeling soil carbon dynamics and greenhouse emissions are also discussed.

Searching for order in atmospheric pressure plasma jets

NASA Astrophysics Data System (ADS)

Schäfer, Jan; Sigeneger, Florian; Šperka, Jiří; Rodenburg, Cornelia; Foest, Rüdiger

2018-01-01

The self-organized discharge behaviour occurring in a non-thermal radio-frequency plasma jet in rare gases at atmospheric pressure was investigated. The frequency of the azimuthal rotation of filaments in the active plasma volume and their inclination were measured along with the gas temperature under varying discharge conditions. The gas flow and heating were described theoretically by a three-dimensional hydrodynamic model. The rotation frequencies obtained by both methods qualitatively agree. The results demonstrate that the plasma filaments forming an inclination angle α with the axial gas velocity u z are forced to a transversal movement with the velocity {u}φ =\\tan (α )\\cdot {u}z, which is oriented in the inclination direction. Variations of {u}φ in the model reveal that the observed dynamics minimizes the energy loss due to convective heat transfer by the gas flow. The control of the self-organization regime motivates the application of the plasma jet for precise and reproducible material processing.

The CALIPSO Borehole Project at Soufrière Hills Volcano, Montserrat, BWI: Status and Scientific Overview of Prodigious Dome Collapse of July 2003

NASA Astrophysics Data System (ADS)

Mattioli, G. S.; Voight, B.; Linde, A. T.; Sacks, I. S.; Watts, P.; Hidayat, D.; Young, S. R.; Widiwijayanti, C.; Shalev, E.; Malin, P. E.; Elsworth, D.; Williams, P.; van Boskirk, E.; Thompson, G.; Syers, T.; Sparks, R. S.; Schleigh, B.; Norton, G.; Neuberg, J.; Miller, V.; McWhorter, N.; Johnston, W.; Dunkley, P.; Clarke, A. B.; Bass, V.

2005-05-01

The CALIPSO Project (Caribbean Andesite Lava Island-volcano Precision Seismo-geodetic Observatory) has greatly enhanced the monitoring and scientific infrastructure at the Soufrière Hills Volcano, Montserrat with the recent installation of an integrated array of borehole and surface geophysical instrumentation at four sites (Mattioli et al., 2004). The sensor package at each site includes: a single-component, very broad band, Sacks-Evertson strainmeter, a three-component seismometer (~Hz to 1 kHz), a Pinnacle Technologies series 5000 tiltmeter, and a surface Ashtech u-Z CGPS station with choke ring antenna, SCIGN mount and radome. The project has been successfully launched with its capture of the tremendous SHV lava dome collapse of 12-13 July 2003 (Herd et al., 2003), involving about 120 million cubic meters--the largest lava dome collapse in the historical record. A wide variety of unique geophysical signals were acquired CALIPSO instrumentation during the July 2003 collapse and important constraints on a variety of volcanic processes are being obtained. For example, tsunami waves were generated 2 km east of the volcanic dome by pyroclastic flows entering the sea. We reconstruct collapse volume-time history from seismic signals generated by pyroclastic flows, using the method of Brodscholl et al. (2000). The tsunami left flotsam strandlines of runup >8m high along the east coast of Montserrat, and waves ~0.5m high were reported from Guadaloupe. Unique borehole dilatometer data (Voight et al., 2003; Mattioli et al., 2003; 2004) record details of tsunami wave passage. One station is located 40m from the sea, with the instrument ~180m below MSL. Strain wave packets at periods of ~200-500s occurred, consistent in period and amplitude with water loading from passing tsunami waves. Wave packets between ~0600-1130 LT can be correlated with pyroclastic flow seismic data. Non-linear Boussinesq hydrodynamic modeling fits wave decay from source to instrument site and is consistent with wave periods and delay times. Coherent near-field waves depend on flow volume, submerged time of motion, and bathymetry. The model matches the delay time between pyroclastic flow entry time and arrival of tsunami waves at the instrument site.

USSR and Eastern Europe Scientific Abstracts, Chemistry, Number 60

DTIC Science & Technology

1978-07-12

OF AROMATIC AND HETEROCYCLIC ANALOGUES OF THE NATURAL GROWTH INHIBITOR - ABSCISIC ACID Tashkent KHIMIYA PRIRODNYKH SOYEDINENIY in Russian No 1, 1978...Chemistry of Natural Products, Academy of Sciences UzSSR, Tashkent [Abstract] Aryl analogues of abscisic acid were obtained by the Reformatskii...heterocyclic nuclei with carboethoxy-methylene- triphenylphosphorane led to the formation of furyl and hetero-cyclic analogues of abscisic acid . The

Studies on Typhus and Spotted Fever

DTIC Science & Technology

1979-02-01

thawing caused no detectaule loss of ricket - tsial infectivity. Accordingly, the longterm survival of typhus organisms at -700 C in these and other...or even qualitative,differentiation between a specific action on intracellular ricket - tsiae and selective cytotoxicity directed against infected...study of the cell envelopes of Rickettsia prowazekii, Rickettsia ricket ii, and Rickettsia tsutsugamushi. Infect. Immun. 21: 1020-1uZ3 (1978). 8

Fiscal Year 2013 Comprehensive Oversight Plan for Southwest Asia

DTIC Science & Technology

2012-09-26

Republic JO Jordan TJ Tajikistan KZ Kazakhstan TM Turkmenistan KW Kuwait AE United Arab Emirates KG Kyrgyzstan UZ Uzbekistan LB Lebanon YE Yemen...effective, responsive, democratic, transparent, accountable, and gender sensitive municipal governance in select municipalities in Afghanistan? (Project...CAII-Creative Associates International, Inc., Ambassador’s Small Grants Program to Support Gender Equality in Afghanistan – ASGP Objective: 306-A-00

Electrical Discharges in Water. A Hydrodynamic Description

DTIC Science & Technology

1974-12-23

obtaln (41.58) Uz;iri!: (41.58), i- Is easy to calculate th, radiated acoustical ener,-y’, t nt1 •re: t i ±" £ : o f enjerF;-y w.! L; rcspec’. to a...wire. hundred atmospheres, it is necessary to apply protective sheathing of the piezocell in order to avoid nonlinear distortions. Piezc- cells in the

A Comparative Study of Entrepreneurship Curriculum Development and Review at the University of Zimbabwe and Botho University, Botswana

ERIC Educational Resources Information Center

Munyanyiwa, Takaruza; Svotwa, Douglas; Rudhumbu, Norman; Mutsau, Morgen

2016-01-01

The purpose of this research was to make comparative study of the development and review process of the entrepreneurship curriculum at the University of Zimbabwe (UZ) Faculty of Commerce and Botho University, (BU) Faculty of Business and Accounting in Gaborone, Botswana. The study focused on the processes and influences of curriculum development…

Prime Contractors with Awards over $25,000 by Name, Location, and Contract Number. Part 6 (RGI Inc, San Diego, California -- Technology Specialist Inc, Arlington, Virginia), FY1991

DTIC Science & Technology

1991-01-01

L) W z WU- L) .4 WCl)L3( 0 WWW < WW W 0i z m I 0 I= 4 C4cc( IU3 U 4n z L) Uz C) 4 Z UZ u -) Utz 0 U 0 0 I -C U 4 U; I4 Cl aW L, L) W9 nE 0- 0 U3W...0 0 I ~ 1j ~ 0> ix ( 0m.- LI)1. (n 0. Z3 Li -C En LI :1 I’" T, CL, 4H H L) Www I L r u - 0- 0 . 0. 8 . > 0 0:000: 104. 10 N0 ) 0 LI L C.4 I L 0 1.. H...m M 0c A 04 4 .4 042 . CC u U) 0 439 4 a.Z-M a 0 C z 4 www 0O > 0~ L) oH 0 g 2 > cn L) 0 44 0 0 Su~A 08 U3H 0 . Z w.~4. CO~ W ’OCCOO) f OC)OC ix0< HI

A framework for evaluating forest landscape model predictions using empirical data and knowledge

Treesearch

Wen J. Wang; Hong S. He; Martin A. Spetich; Stephen R. Shifley; Frank R. Thompson; William D. Dijak; Qia Wang

2014-01-01

Evaluation of forest landscape model (FLM) predictions is indispensable to establish the credibility of predictions. We present a framework that evaluates short- and long-term FLM predictions at site and landscape scales. Site-scale evaluation is conducted through comparing raster cell-level predictions with inventory plot data whereas landscape-scale evaluation is...

Doubly stochastic Poisson process models for precipitation at fine time-scales

NASA Astrophysics Data System (ADS)

Ramesh, Nadarajah I.; Onof, Christian; Xie, Dichao

2012-09-01

This paper considers a class of stochastic point process models, based on doubly stochastic Poisson processes, in the modelling of rainfall. We examine the application of this class of models, a neglected alternative to the widely-known Poisson cluster models, in the analysis of fine time-scale rainfall intensity. These models are mainly used to analyse tipping-bucket raingauge data from a single site but an extension to multiple sites is illustrated which reveals the potential of this class of models to study the temporal and spatial variability of precipitation at fine time-scales.

Department of Defense Data Model, Version 1, Fy 1998, Volume 2.

DTIC Science & Technology

1998-05-31

tDC ^Sg ujs-ijg ^ ^ Z uj UJ ooätb UJ UJ X DC DC a a v> a a o o o XXX LU LU LU > > > ODD LU LU LU z z z OO o x x UJ x LU UJ Q LU D...oog 00=3 * I- U-.Z ^ Tm UJ uj u. UJ PX z2 UJ < 96 HZ Zh Ul o E< UJ DC UJ I- oc z oo < o 1- uj! ps s< l-O ZC3 O UJ oz _l _l...zzi => = b o o z EEg <ɡ Q UI I- LUOO b > s < OcLbz EazO << = o UI Ul Ul UI ui l- D X OS "z Eil ?u «ES

Res-E Support Policies in the Baltic States: Electricity Price Aspect (Part II)

NASA Astrophysics Data System (ADS)

Bobinaite, V.; Priedite, I.

2015-04-01

Increasing volumes of electricity derived from renewable energy sources (RES-E) affect the electricity market prices and the prices for final electricity consumers in the Baltic States. The results of a multivariate regression analysis show that in 2013 the RES-E contributed to decreasing the electricity market prices in the Baltic States. However, the final electricity consumers pay for the promotion of RES-E through the approved RES-E component which has a tendency to increase. It is estimated that in 2013 the net benefits from the wind electricity promotion were achieved in Lithuania and Latvia while the net cost - in Estonia. This suggests that the economic efficiency of the wind electricity support scheme based on the application of feed-in tariffs was higher than that based on the feed-in premium. Rakstā analizēta elektroenerģijas ražošanas no atjaunojamiem energoresursiem (AER-E) palielināšanas ietekme uz elektroenerģijas tirgus cenu un gala cenu elektroenerģijas lietotājiem Baltijas valstīs. Daudzfaktoru regresijas analīzes rezultāti atklāja, ka AER-E 2013. gadā varētu samazināt elektroenerģijas tirgus cenas Baltijas valstīs. Tomēr jāņem vērā, ka elektroenerģijas lietotāja gala cenā ir iekļauta AER-E atbalsta komponente, kurai ir raksturīgi palielināties. Aprēķināts, ka no vēja elektroenerģijas ražošanas Latvijā un Lietuvā tika iegūta tīrā peļņa, bet Igaunijā tikai nosedza pašizmaksu. Tas liecina, ka vēja elektroenerģijas atbalsta shēmai, kas balstīta uz obligātā iepirkuma atbalsta principu, ir augstāka ekonomiskā efektivitāte, nekā atbalsta shēmai, kas balstīta uz piemaksu par no AER saražoto elektroenerģiju obligātā iepirkuma ietvaros.

Bridging Scales: A Model-Based Assessment of the Technical Tidal-Stream Energy Resource off Massachusetts, USA

NASA Astrophysics Data System (ADS)

Cowles, G. W.; Hakim, A.; Churchill, J. H.

2016-02-01

Tidal in-stream energy conversion (TISEC) facilities provide a highly predictable and dependable source of energy. Given the economic and social incentives to migrate towards renewable energy sources there has been tremendous interest in the technology. Key challenges to the design process stem from the wide range of problem scales extending from device to array. In the present approach we apply a multi-model approach to bridge the scales of interest and select optimal device geometries to estimate the technical resource for several realistic sites in the coastal waters of Massachusetts, USA. The approach links two computational models. To establish flow conditions at site scales ( 10m), a barotropic setup of the unstructured grid ocean model FVCOM is employed. The model is validated using shipboard and fixed ADCP as well as pressure data. For device scale, the structured multiblock flow solver SUmb is selected. A large ensemble of simulations of 2D cross-flow tidal turbines is used to construct a surrogate design model. The surrogate model is then queried using velocity profiles extracted from the tidal model to determine the optimal geometry for the conditions at each site. After device selection, the annual technical yield of the array is evaluated with FVCOM using a linear momentum actuator disk approach to model the turbines. Results for several key Massachusetts sites including comparison with theoretical approaches will be presented.

A catchment scale water balance model for FIFE

NASA Technical Reports Server (NTRS)

Famiglietti, J. S.; Wood, E. F.; Sivapalan, M.; Thongs, D. J.

1992-01-01

A catchment scale water balance model is presented and used to predict evaporation from the King's Creek catchment at the First ISLSCP Field Experiment site on the Konza Prairie, Kansas. The model incorporates spatial variability in topography, soils, and precipitation to compute the land surface hydrologic fluxes. A network of 20 rain gages was employed to measure rainfall across the catchment in the summer of 1987. These data were spatially interpolated and used to drive the model during storm periods. During interstorm periods the model was driven by the estimated potential evaporation, which was calculated using net radiation data collected at site 2. Model-computed evaporation is compared to that observed, both at site 2 (grid location 1916-BRS) and the catchment scale, for the simulation period from June 1 to October 9, 1987.

Observation and modelling of urban dew

NASA Astrophysics Data System (ADS)

Richards, Katrina

Despite its relevance to many aspects of urban climate and to several practical questions, urban dew has largely been ignored. Here, simple observations an out-of-doors scale model, and numerical simulation are used to investigate patterns of dewfall and surface moisture (dew + guttation) in urban environments. Observations and modelling were undertaken in Vancouver, B.C., primarily during the summers of 1993 and 1996. Surveys at several scales (0.02-25 km) show that the main controls on dew are weather, location and site configuration (geometry and surface materials). Weather effects are discussed using an empirical factor, FW . Maximum dew accumulation (up to ~ 0.2 mm per night) is seen on nights with moist air and high FW , i.e., cloudless conditions with light winds. Favoured sites are those with high Ysky and surfaces which cool rapidly after sunset, e.g., grass and well insulated roofs. A 1/8-scale model is designed, constructed, and run at an out-of-doors site to study dew patterns in an urban residential landscape which consists of house lots, a street and an open grassed park. The Internal Thermal Mass (ITM) approach is used to scale the thermal inertia of buildings. The model is validated using data from full-scale sites in Vancouver. Patterns in the model agree with those seen at the full-scale, i.e., dew distribution is governed by weather, site geometry and substrate conditions. Correlation is shown between Ysky and surface moisture accumulation. The feasibility of using a numerical model to simulate urban dew is investigated using a modified version of a rural dew model. Results for simple isolated surfaces-a deciduous tree leaf and an asphalt shingle roof-show promise, especially for built surfaces.

Creative use of pilot points to address site and regional scale heterogeneity in a variable-density model

USGS Publications Warehouse

Dausman, Alyssa M.; Doherty, John; Langevin, Christian D.

2010-01-01

Pilot points for parameter estimation were creatively used to address heterogeneity at both the well field and regional scales in a variable-density groundwater flow and solute transport model designed to test multiple hypotheses for upward migration of fresh effluent injected into a highly transmissive saline carbonate aquifer. Two sets of pilot points were used within in multiple model layers, with one set of inner pilot points (totaling 158) having high spatial density to represent hydraulic conductivity at the site, while a second set of outer points (totaling 36) of lower spatial density was used to represent hydraulic conductivity further from the site. Use of a lower spatial density outside the site allowed (1) the total number of pilot points to be reduced while maintaining flexibility to accommodate heterogeneity at different scales, and (2) development of a model with greater areal extent in order to simulate proper boundary conditions that have a limited effect on the area of interest. The parameters associated with the inner pilot points were log transformed hydraulic conductivity multipliers of the conductivity field obtained by interpolation from outer pilot points. The use of this dual inner-outer scale parameterization (with inner parameters constituting multipliers for outer parameters) allowed smooth transition of hydraulic conductivity from the site scale, where greater spatial variability of hydraulic properties exists, to the regional scale where less spatial variability was necessary for model calibration. While the model is highly parameterized to accommodate potential aquifer heterogeneity, the total number of pilot points is kept at a minimum to enable reasonable calibration run times.

Measured and modelled leaf and stand-scale productivity across a soil moisture gradient and a severe drought.

PubMed

Wright, J K; Williams, M; Starr, G; McGee, J; Mitchell, R J

2013-02-01

Environmental controls on carbon dynamics operate at a range of interacting scales from the leaf to landscape. The key questions of this study addressed the influence of water and nitrogen (N) availability on Pinus palustris (Mill.) physiology and primary productivity across leaf and canopy scales, linking the soil-plant-atmosphere (SPA) model to leaf and stand-scale flux and leaf trait/canopy data. We present previously unreported ecophysiological parameters (e.g. V(cmax) and J(max)) for P. palustris and the first modelled estimates of its annual gross primary productivity (GPP) across xeric and mesic sites and under extreme drought. Annual mesic site P. palustris GPP was ∼23% greater than at the xeric site. However, at the leaf level, xeric trees had higher net photosynthetic rates, and water and light use efficiency. At the canopy scale, GPP was limited by light interception (canopy level), but co-limited by nitrogen and water at the leaf level. Contrary to expectations, the impacts of an intense growing season drought were greater at the mesic site. Modelling indicated a 10% greater decrease in mesic GPP compared with the xeric site. Xeric P. palustris trees exhibited drought-tolerant behaviour that contrasted with mesic trees' drought-avoidance behaviour. © 2012 Blackwell Publishing Ltd.

Oceanographic and Acoustical Survey of the East Ionian Sea

DTIC Science & Technology

1990-09-01

Notation The views expressed-in this thesis are those of the author and do not reflect the official policy or po- sition -of-the Department of Defense...8217 ,_ ,=--- . OLo • :. LU _ -09 5 /- S US8 0)6 0 • OU G I:: -CD *.. LU Uz CD_ _ _ Li C) . LU M -- cN C.8 C C - ------- CD CnCD C:) C81 m 0- ’an 0 0

General Urban Warfare Amphibious Logistics Applications. Volume 3. Operational Plans.

DTIC Science & Technology

1983-06-23

should be provided such as fruit , vegetables, condi- ments, tea, powdered milk, etc. These will be in short supply, but the Food and Agriculture...I I I(W; PERIO& VII L061TlUN. 5’rN CITr RAILGU OF RCIIC.Uz= Z.40 KILOMETERS E51PLY LITU5T~C= 4.0 ±2kILOWTER5 LENGTii CF PERIC@.D- 25 )WS- 55TEP1

Internally driven inertial waves in geodynamo simulations

NASA Astrophysics Data System (ADS)

Ranjan, A.; Davidson, P. A.; Christensen, U. R.; Wicht, J.

2018-05-01

Inertial waves are oscillations in a rotating fluid, such as the Earth's outer core, which result from the restoring action of the Coriolis force. In an earlier work, it was argued by Davidson that inertial waves launched near the equatorial regions could be important for the α2 dynamo mechanism, as they can maintain a helicity distribution which is negative (positive) in the north (south). Here, we identify such internally driven inertial waves, triggered by buoyant anomalies in the equatorial regions in a strongly forced geodynamo simulation. Using the time derivative of vertical velocity, ∂uz/∂t, as a diagnostic for traveling wave fronts, we find that the horizontal movement in the buoyancy field near the equator is well correlated with a corresponding movement of the fluid far from the equator. Moreover, the azimuthally averaged spectrum of ∂uz/∂t lies in the inertial wave frequency range. We also test the dispersion properties of the waves by computing the spectral energy as a function of frequency, ϖ, and the dispersion angle, θ. Our results suggest that the columnar flow in the rotation-dominated core, which is an important ingredient for the maintenance of a dipolar magnetic field, is maintained despite the chaotic evolution of the buoyancy field on a fast timescale by internally driven inertial waves.

Results of Measurements of Accelerations of Technological Devices onboard the FotonSpacecraft

NASA Astrophysics Data System (ADS)

Barmin, I. V.; Volkov, M. V.; Egorov, A. V.; Reut, E. F.; Senchenkov, A. S.

2001-07-01

This paper generalizes the results of measuring the residual accelerations arising when investigations in space materials science are carried out onboard the unmanned Fotonspacecraft. The levels of vibroaccelerations are analyzed in the frequency band of 1 500 Hz for the technological devices UZ01, UZ04, and POLIZON, developed by the Federal Unitary State Enterprise “Barmin Design Bureau of General Machine Building” (V.P. Barmin KBOM). The levels of accelerations are estimated in the frequency band of 0 1 Hz in the zone of technological operations of these facilities. The basic sources of vibroaccelerations acting upon the frames of devices are determined in the capsule zone, where technological processes of producing new materials take place. In the frequency band of 1 500 Hz the vibroaccelerations are shown to be generated by the operation of Fotonspacecraft units and a drive of capsule translation during the technological process. On the capsule frame they reach the values of (1 3) × 10 3 g. The level of linear accelerations in the infralow-frequency band is determined by rotational motions of the Fotonspacecraft. It depends on the device location with respect to the spacecraft center of mass and does not exceed (1 7) × 10 6 gin the steady-state regime in the zone of technological activity.

Optimal-adaptive filters for modelling spectral shape, site amplification, and source scaling

USGS Publications Warehouse

Safak, Erdal

1989-01-01

This paper introduces some applications of optimal filtering techniques to earthquake engineering by using the so-called ARMAX models. Three applications are presented: (a) spectral modelling of ground accelerations, (b) site amplification (i.e., the relationship between two records obtained at different sites during an earthquake), and (c) source scaling (i.e., the relationship between two records obtained at a site during two different earthquakes). A numerical example for each application is presented by using recorded ground motions. The results show that the optimal filtering techniques provide elegant solutions to above problems, and can be a useful tool in earthquake engineering.

Seismic risk assessment for Poiana Uzului (Romania) buttress dam on Uz river

NASA Astrophysics Data System (ADS)

Moldovan, Iren-Adelina; Toma-Danila, Dragos; Paerele, Cosmin Marian; Emilian Toader, Victorin; Petruta Constantin, Angela; Ghita, Cristian

2017-04-01

The most important specific requirements towards dams' safety is the seismic risk assessment. This objective will be accomplished by rating the dams into seismic risk classes using the theory of Bureau and Ballentine, 2002, and Bureau (2003), taking into account the maximum expected peak ground motions at dams' site, the structures vulnerability and the downstream risk characteristics. The maximum expected values for ground motions at dams' site have been obtained using probabilistic seismic hazard assessment approaches. The structural vulnerability was obtained from dams' characteristics (age, high, water volume) and the downstream risk was assessed using human, economical, touristic, historic and cultural heritage information from the areas that might be flooded in the case of a dam failure. A couple of flooding scenarios have been performed. The results of the work consist of local and regional seismic information, specific characteristics of dam, seismic hazard values for different return periods and risk classes. The studies realized in this paper have as final goal to provide in the near future the local emergency services with warnings of a potential dam failure and ensuing flood as a result of a large earthquake occurrence, allowing further public training for evacuation. Acknowledgments This work was partially supported by the Partnership in Priority Areas Program - PNII, under MEN-UEFISCDI, DARING Project no. 69/2014 and the Nucleu Program - PN 16-35, Project no. 03 01 and 01 06.

Robust Multivariable Controller Design via Implicit Model-Following Methods.

DTIC Science & Technology

1983-12-01

followers, such as: II-7 , Ai ".......... . - ,. * . . , -. ,., 4’ . L7 XJ •:-, - J - / ( -+(Y -m)-- ( _ym + UTUc-]dt (11-13) A design method based on...Im r4 aI AI wS I I C.) 0 N 0N ON0N% I4 A’. I 0L- t-00 o% 0 ON 000 LA0 Naj UzN W4 c * r- In Go .% m * m . \\ C-. 0 cm a 0 ’no L- 00 *- \\ 14 0 0 ’-C Go N...0 t’. ~ - V’’. LALA -f . ONZ LA 41 0 \\ NL 0n I a A A N aI ’ nN? Z . =. 4 1 -I -0 I. I %a .0 1 - .a to. ot .b t o ob oto ob o11 cc-. "-f cccX dc c t I

Multiscale Processes in Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Surjalal Sharma, A.; Jain, Neeraj

The characteristic scales of the plasma processes in magnetic reconnection range from the elec-tron skin-depth to the magnetohydrodynamic (MHD) scale, and cross-scale coupling among them play a key role. Modeling these processes requires different physical models, viz. kinetic, electron-magnetohydrodynamics (EMHD), Hall-MHD, and MHD. The shortest scale processes are at the electron scale and these are modeled using an EMHD code, which provides many features of the multiscale behavior. In simulations using initial conditions consisting of pertur-bations with many scale sizes the reconnection takes place at many sites and the plasma flows from these interact with each other. This leads to thin current sheets with length less than 10 electron skin depths. The plasma flows also generate current sheets with multiple peaks, as observed by Cluster. The quadrupole structure of the magnetic field during reconnection starts on the electron scale and the interaction of inflow to the secondary sites and outflow from the dominant site generates a nested structure. In the outflow regions, the interaction of the electron outflows generated at the neighboring sites lead to the development of electron vortices. A signature of the nested structure of the Hall field is seen in Cluster observations, and more details of these features are expected from MMS.

Magnetospheric Accretion in Close Pre-main-sequence Binaries

NASA Astrophysics Data System (ADS)

Ardila, David R.; Jonhs-Krull, Christopher; Herczeg, Gregory J.; Mathieu, Robert D.; Quijano-Vodniza, Alberto

2015-10-01

The transfer of matter between a circumbinary disk and a young binary system remains poorly understood, obscuring the interpretation of accretion indicators. To explore the behavior of these indicators in multiple systems, we have performed the first systematic time-domain study of young binaries in the ultraviolet. We obtained far- and near-ultraviolet HST/COS spectra of the young spectroscopic binaries DQ Tau and UZ Tau E. Here we focus on the continuum from 2800 to 3200 Å and on the C iv doublet (λλ1548.19, 1550.77 Å) as accretion diagnostics. Each system was observed over three or four consecutive binary orbits, at phases ∼0, 0.2, 0.5, and 0.7. Those observations are complemented by ground-based U-band measurements. Contrary to model predictions, we do not detect any clear correlation between accretion luminosity and phase. Further, we do not detect any correlation between C iv flux and phase. For both stars the appearance of the C iv line is similar to that of single Classical T Tauri Stars (CTTSs), despite the lack of stable long-lived circumstellar disks. However, unlike the case in single CTTSs, the narrow and broad components of the C iv lines are uncorrelated, and we argue that the narrow component is powered by processes other than accretion, such as flares in the stellar magnetospheres and/or enhanced activity in the upper atmosphere. We find that both stars contribute equally to the narrow component C iv flux in DQ Tau, but the primary dominates the narrow component C iv emission in UZ Tau E. The C iv broad component flux is correlated with other accretion indicators, suggesting an accretion origin. However, the line is blueshifted, which is inconsistent with its origin in an infall flow close to the star. It is possible that the complicated geometry of the region, as well as turbulence in the shock region, are responsible for the blueshifted line profiles.

Power Dynamics in Applied Theatre: Interrogating the Power of the University-Based TfD Facilitator--the UZ Theatre and CARE Zimbabwe's Zvishavane/Mberengwa NICA Project and SSFP as Case Study

ERIC Educational Resources Information Center

Seda, Owen; Chivandikwa, Nehemiah

2014-01-01

One of the central tenets in applied theatre is the ability to confront issues of "power" and "powerlessness." Indeed, success or lack thereof in applied theatre projects is often adjudged against the ability or the extent to which these projects are, or have been able to "empower" the "powerless." In this…

Estimation of surface heat and moisture fluxes over a prairie grassland. II - Two-dimensional time filtering and site variability

NASA Technical Reports Server (NTRS)

Crosson, William L.; Smith, Eric A.

1992-01-01

The behavior of in situ measurements of surface fluxes obtained during FIFE 1987 is examined by using correlative and spectral techniques in order to assess the significance of fluctuations on various time scales, from subdiurnal up to synoptic, intraseasonal, and annual scales. The objectives of this analysis are: (1) to determine which temporal scales have a significant impact on areal averaged fluxes and (2) to design a procedure for filtering an extended flux time series that preserves the basic diurnal features and longer time scales while removing high frequency noise that cannot be attributed to site-induced variation. These objectives are accomplished through the use of a two-dimensional cross-time Fourier transform, which serves to separate processes inherently related to diurnal and subdiurnal variability from those which impact flux variations on the longer time scales. A filtering procedure is desirable before the measurements are utilized as input with an experimental biosphere model, to insure that model based intercomparisons at multiple sites are uncontaminated by input variance not related to true site behavior. Analysis of the spectral decomposition indicates that subdiurnal time scales having periods shorter than 6 hours have little site-to-site consistency and therefore little impact on areal integrated fluxes.

A Hierarchical Analysis of Tree Growth and Environmental Drivers Across Eastern US Temperate Forests

NASA Astrophysics Data System (ADS)

Mantooth, J.; Dietze, M.

2014-12-01

Improving predictions of how forests in the eastern United States will respond to future global change requires a better understanding of the drivers of variability in tree growth rates. Current inventory data lack the temporal resolution to characterize interannual variability, while existing growth records lack the extent required to assess spatial scales of variability. Therefore, we established a network of forest inventory plots across ten sites across the eastern US, and measured growth in adult trees using increment cores. Sites were chosen to maximize climate space explored, while within sites, plots were spread across primary environmental gradients to explore landscape-level variability in growth. Using the annual growth record available from tree cores, we explored the responses of trees to multiple environmental covariates over multiple spatial and temporal scales. We hypothesized that within and across sites growth rates vary among species, and that intraspecific growth rates increase with temperature along a species' range. We also hypothesized that trees show synchrony in growth responses to landscape-scale climatic changes. Initial analyses of growth increments indicate that across sites, trees with intermediate shade tolerance, e.g. Red Oak (Quercus rubra), tend to have the highest growth rates. At the site level, there is evidence for synchrony in response to large-scale climatic events (e.g. prolonged drought and above average temperatures). However, growth responses to climate at the landscape scale have yet to be detected. Our current analysis utilizes hierarchical Bayesian state-space modeling to focus on growth responses of adult trees to environmental covariates at multiple spatial and temporal scales. This predictive model of tree growth currently incorporates observed effects at the individual, plot, site, and landscape scale. Current analysis using this model shows a potential slowing of growth in the past decade for two sites in the northeastern US (Harvard Forest and Bartlett Experimental Forest), however more work is required to determine the robustness of this trend. Finally, these observations are being incorporated into ecosystem models using the Brown Dog informatics tools and the Predictive Ecosystem Analyzer (PEcAn) data assimilation workflow.

Managing data from multiple disciplines, scales, and sites to support synthesis and modeling

USGS Publications Warehouse

Olson, R. J.; Briggs, J. M.; Porter, J.H.; Mah, Grant R.; Stafford, S.G.

1999-01-01

The synthesis and modeling of ecological processes at multiple spatial and temporal scales involves bringing together and sharing data from numerous sources. This article describes a data and information system model that facilitates assembling, managing, and sharing diverse data from multiple disciplines, scales, and sites to support integrated ecological studies. Cross-site scientific-domain working groups coordinate the development of data associated with their particular scientific working group, including decisions about data requirements, data to be compiled, data formats, derived data products, and schedules across the sites. The Web-based data and information system consists of nodes for each working group plus a central node that provides data access, project information, data query, and other functionality. The approach incorporates scientists and computer experts in the working groups and provides incentives for individuals to submit documented data to the data and information system.

On temporal stochastic modeling of precipitation, nesting models across scales

NASA Astrophysics Data System (ADS)

Paschalis, Athanasios; Molnar, Peter; Fatichi, Simone; Burlando, Paolo

2014-01-01

We analyze the performance of composite stochastic models of temporal precipitation which can satisfactorily reproduce precipitation properties across a wide range of temporal scales. The rationale is that a combination of stochastic precipitation models which are most appropriate for specific limited temporal scales leads to better overall performance across a wider range of scales than single models alone. We investigate different model combinations. For the coarse (daily) scale these are models based on Alternating renewal processes, Markov chains, and Poisson cluster models, which are then combined with a microcanonical Multiplicative Random Cascade model to disaggregate precipitation to finer (minute) scales. The composite models were tested on data at four sites in different climates. The results show that model combinations improve the performance in key statistics such as probability distributions of precipitation depth, autocorrelation structure, intermittency, reproduction of extremes, compared to single models. At the same time they remain reasonably parsimonious. No model combination was found to outperform the others at all sites and for all statistics, however we provide insight on the capabilities of specific model combinations. The results for the four different climates are similar, which suggests a degree of generality and wider applicability of the approach.

Sub-seasonal-to-seasonal Reservoir Inflow Forecast using Bayesian Hierarchical Hidden Markov Model

NASA Astrophysics Data System (ADS)

Mukhopadhyay, S.; Arumugam, S.

2017-12-01

Sub-seasonal-to-seasonal (S2S) (15-90 days) streamflow forecasting is an emerging area of research that provides seamless information for reservoir operation from weather time scales to seasonal time scales. From an operational perspective, sub-seasonal inflow forecasts are highly valuable as these enable water managers to decide short-term releases (15-30 days), while holding water for seasonal needs (e.g., irrigation and municipal supply) and to meet end-of-the-season target storage at a desired level. We propose a Bayesian Hierarchical Hidden Markov Model (BHHMM) to develop S2S inflow forecasts for the Tennessee Valley Area (TVA) reservoir system. Here, the hidden states are predicted by relevant indices that influence the inflows at S2S time scale. The hidden Markov model also captures the both spatial and temporal hierarchy in predictors that operate at S2S time scale with model parameters being estimated as a posterior distribution using a Bayesian framework. We present our work in two steps, namely single site model and multi-site model. For proof of concept, we consider inflows to Douglas Dam, Tennessee, in the single site model. For multisite model we consider reservoirs in the upper Tennessee valley. Streamflow forecasts are issued and updated continuously every day at S2S time scale. We considered precipitation forecasts obtained from NOAA Climate Forecast System (CFSv2) GCM as predictors for developing S2S streamflow forecasts along with relevant indices for predicting hidden states. Spatial dependence of the inflow series of reservoirs are also preserved in the multi-site model. To circumvent the non-normality of the data, we consider the HMM in a Generalized Linear Model setting. Skill of the proposed approach is tested using split sample validation against a traditional multi-site canonical correlation model developed using the same set of predictors. From the posterior distribution of the inflow forecasts, we also highlight different system behavior under varied global and local scale climatic influences from the developed BHMM.

Direct and indirect effects of multiple stressors on stream invertebrates across watershed, reach and site scales: A structural equation modelling better informing on hydromorphological impacts.

PubMed

Villeneuve, B; Piffady, J; Valette, L; Souchon, Y; Usseglio-Polatera, P

2018-01-15

The purpose of our approach was to take into account the nested spatial scales driving stream functioning in the description of pressures/ecological status links by analysing the results of a hierarchical model. The development of this model has allowed us to answer the following questions: Does the consideration of the indirect links between anthropogenic pressures and stream ecological status modify the hierarchy of pressure types impacting benthic invertebrates? Do the different nested scales play different roles in the anthropogenic pressures/ecological status relationship? Does this model lead to better understanding of the specific role of hydromorphology in the evaluation of stream ecological status? To achieve that goal, we used the Partial Least Square (PLS) path modelling method to develop a structural model linking variables describing (i) land use and hydromorphological alterations at the watershed scale, (ii) hydromorphological alterations at the reach scale, (iii) nutrients-organic matter contamination levels at the site scale, and (iv) substrate characteristics at the sampling site scale, to explain variation in values of a macroinvertebrate-based multimetric index: the French I 2 M 2 . We have highlighted the importance of land use effects exerted on both hydromorphological and chemical characteristics of streams observed at finer scales and their subsequent indirect impact on stream ecological status. Hydromorphological alterations have an effect on the substrate mosaic structure and on the concentrations of nutrients and organic matter at site scale. This result implies that stream hydromorphology can have a major indirect effect on macroinvertebrate assemblages and that the hierarchy of impacts of anthropogenic pressures on stream ecological status generally described in the literature - often determining strategic restoration priorities - has to be re-examined. Finally, the effects of nutrients and organic matter on macroinvertebrate assemblages are lower than expected when all the indirect effects of land use and hydromorphological alterations are taken into account. Copyright © 2017 Elsevier B.V. All rights reserved.

Contrasting patterns of fine-scale herb layer species composition in temperate forests

NASA Astrophysics Data System (ADS)

Chudomelová, Markéta; Zelený, David; Li, Ching-Feng

2017-04-01

Although being well described at the landscape level, patterns in species composition of forest herb layer are rarely studied at smaller scales. Here, we examined fine-scale environmental determinants and spatial structures of herb layer communities in thermophilous oak- and hornbeam dominated forests of the south-eastern part of the Czech Republic. Species composition of herb layer vegetation and environmental variables were recorded within a fixed grid of 2 × 2 m subplots regularly distributed within 1-ha quadrate plots in three forest stands. For each site, environmental models best explaining species composition were constructed using constrained ordination analysis. Spatial eigenvector mapping was used to model and account for spatial structures in community variation. Mean Ellenberg indicator values calculated for each subplot were used for ecological interpretation of spatially structured residual variation. The amount of variation explained by environmental and spatial models as well as the selection of variables with the best explanatory power differed among sites. As an important environmental factor, relative elevation was common to all three sites, while pH and canopy openness were shared by two sites. Both environmental and community variation was mostly coarse-scaled, as was the spatially structured portion of residual variation. When corrected for bias due to spatial autocorrelation, those environmental factors with already weak explanatory power lost their significance. Only a weak evidence of possibly omitted environmental predictor was found for autocorrelated residuals of site models using mean Ellenberg indicator values. Community structure was determined by different factors at different sites. The relative importance of environmental filtering vs. spatial processes was also site specific, implying that results of fine-scale studies tend to be shaped by local conditions. Contrary to expectations based on other studies, overall dominance of spatial processes at fine scale has not been detected. Ecologists should keep this in mind when making generalizations about community dynamics.

A predictive nondestructive model for the covariation of tree height, diameter, and stem volume scaling relationships.

PubMed

Zhang, Zhongrui; Zhong, Quanlin; Niklas, Karl J; Cai, Liang; Yang, Yusheng; Cheng, Dongliang

2016-08-24

Metabolic scaling theory (MST) posits that the scaling exponents among plant height H, diameter D, and biomass M will covary across phyletically diverse species. However, the relationships between scaling exponents and normalization constants remain unclear. Therefore, we developed a predictive model for the covariation of H, D, and stem volume V scaling relationships and used data from Chinese fir (Cunninghamia lanceolata) in Jiangxi province, China to test it. As predicted by the model and supported by the data, normalization constants are positively correlated with their associated scaling exponents for D vs. V and H vs. V, whereas normalization constants are negatively correlated with the scaling exponents of H vs. D. The prediction model also yielded reliable estimations of V (mean absolute percentage error = 10.5 ± 0.32 SE across 12 model calibrated sites). These results (1) support a totally new covariation scaling model, (2) indicate that differences in stem volume scaling relationships at the intra-specific level are driven by anatomical or ecophysiological responses to site quality and/or management practices, and (3) provide an accurate non-destructive method for predicting Chinese fir stem volume.

Development and field validation of a regional, management-scale habitat model: A koala Phascolarctos cinereus case study.

PubMed

Law, Bradley; Caccamo, Gabriele; Roe, Paul; Truskinger, Anthony; Brassil, Traecey; Gonsalves, Leroy; McConville, Anna; Stanton, Matthew

2017-09-01

Species distribution models have great potential to efficiently guide management for threatened species, especially for those that are rare or cryptic. We used MaxEnt to develop a regional-scale model for the koala Phascolarctos cinereus at a resolution (250 m) that could be used to guide management. To ensure the model was fit for purpose, we placed emphasis on validating the model using independently-collected field data. We reduced substantial spatial clustering of records in coastal urban areas using a 2-km spatial filter and by modeling separately two subregions separated by the 500-m elevational contour. A bias file was prepared that accounted for variable survey effort. Frequency of wildfire, soil type, floristics and elevation had the highest relative contribution to the model, while a number of other variables made minor contributions. The model was effective in discriminating different habitat suitability classes when compared with koala records not used in modeling. We validated the MaxEnt model at 65 ground-truth sites using independent data on koala occupancy (acoustic sampling) and habitat quality (browse tree availability). Koala bellows ( n  = 276) were analyzed in an occupancy modeling framework, while site habitat quality was indexed based on browse trees. Field validation demonstrated a linear increase in koala occupancy with higher modeled habitat suitability at ground-truth sites. Similarly, a site habitat quality index at ground-truth sites was correlated positively with modeled habitat suitability. The MaxEnt model provided a better fit to estimated koala occupancy than the site-based habitat quality index, probably because many variables were considered simultaneously by the model rather than just browse species. The positive relationship of the model with both site occupancy and habitat quality indicates that the model is fit for application at relevant management scales. Field-validated models of similar resolution would assist in guiding management of conservation-dependent species.

Perturbations and gradients as fundamental tests for modeling the soil carbon cycle

NASA Astrophysics Data System (ADS)

Bond-Lamberty, B. P.; Bailey, V. L.; Becker, K.; Fansler, S.; Hinkle, C.; Liu, C.

2013-12-01

An important step in matching process-level knowledge to larger-scale measurements and model results is to challenge those models with site-specific perturbations and/or changing environmental conditions. Here we subject modified versions of an ecosystem process model to two stringent tests: replicating a long-term climate change dryland experiment (Rattlesnake Mountain) and partitioning the carbon fluxes of a soil drainage gradient in the northern Everglades (Disney Wilderness Preserve). For both sites, on-site measurements were supplemented by laboratory incubations of soil columns. We used a parameter-space search algorithm to optimize, within observational limits, the model's influential inputs, so that the spun-up carbon stocks and fluxes matched observed values. Modeled carbon fluxes (net primary production and net ecosystem exchange) agreed with measured values, within observational error limits, but the model's partitioning of soil fluxes (autotrophic versus heterotrophic), did not match laboratory measurements from either site. Accounting for site heterogeneity at DWP, modeled carbon exchange was reasonably consistent with values from eddy covariance. We discuss the implications of this work for ecosystem- to global scale modeling of ecosystems in a changing climate.

Improving catchment discharge predictions by inferring flow route contributions from a nested-scale monitoring and model setup

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2011-03-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for the estimation of flow route volumes and for predictions of catchment discharge. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from the hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements improves simulations of nitrate loads and predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

Controls on seasonal patterns of maximum ecosystem carbon uptake and canopy-scale photosynthetic light response: contributions from both temperature and photoperiod.

PubMed

Stoy, Paul C; Trowbridge, Amy M; Bauerle, William L

2014-02-01

Most models of photosynthetic activity assume that temperature is the dominant control over physiological processes. Recent studies have found, however, that photoperiod is a better descriptor than temperature of the seasonal variability of photosynthetic physiology at the leaf scale. Incorporating photoperiodic control into global models consequently improves their representation of the seasonality and magnitude of atmospheric CO2 concentration. The role of photoperiod versus that of temperature in controlling the seasonal variability of photosynthetic function at the canopy scale remains unexplored. We quantified the seasonal variability of ecosystem-level light response curves using nearly 400 site years of eddy covariance data from over eighty Free Fair-Use sites in the FLUXNET database. Model parameters describing maximum canopy CO2 uptake and the initial slope of the light response curve peaked after peak temperature in about 2/3 of site years examined, emphasizing the important role of temperature in controlling seasonal photosynthetic function. Akaike's Information Criterion analyses indicated that photoperiod should be included in models of seasonal parameter variability in over 90% of the site years investigated here, demonstrating that photoperiod also plays an important role in controlling seasonal photosynthetic function. We also performed a Granger causality analysis on both gross ecosystem productivity (GEP) and GEP normalized by photosynthetic photon flux density (GEP n ). While photoperiod Granger-caused GEP and GEP n in 99 and 92% of all site years, respectively, air temperature Granger-caused GEP in a mere 32% of site years but Granger-caused GEP n in 81% of all site years. Results demonstrate that incorporating photoperiod may be a logical step toward improving models of ecosystem carbon uptake, but not at the expense of including enzyme kinetic-based temperature constraints on canopy-scale photosynthesis.

A Study of Strategic Lessons Learned in Vietnam. Volume I. The Enemy

DTIC Science & Technology

1979-11-30

which resulted from the various topical analyses are de -- rived from and related directly to America’s twenty-five year involvement irn Southeast Asia...CAUSED BY GREAT FIRST NUCLEAR REVOLUTION DES "A SEEKS LEAP AND WITHDRAWAL DEVICE NIXON "DER OF SOVIET AID VISIT II•IMPERIALISM SINO.INDIAN VI ANTI...ISRAELICONGRESS. SPUTNIK LANDING CUBAN FAIL.2 DE -STALINIZATIONBAOFPGCRSSLSE UZ UNVEILED. U.2 PLANE KHRUSHCHEV USSR AID TO DRY VISITS HIINGARY INVADED

A History of The U.S. Army in Operations Research

DTIC Science & Technology

1967-05-22

Evolution (1951 - 1959). • • . • • • 60 5. Operations Research Office Organizatin I April 195L4 . . 64 6. AMry Organization for Reseavh and Development...23bid.. pp. 30-31, 41-42. Zpp. 48-50. 41 Thu Office established in Oahu, Hawaii, under the leadership of Dv. Lauriston C, Marshall, a physicist from...research in training methods, motivation, xorale leadership and psychological warfare. Most of the specific problems uz- dertaken by HaRO were old

Tritium Fluxes through the Shallow Unsaturated Zone adjacent to a Radioactive Waste Disposal Facility in an Arid Environment

NASA Astrophysics Data System (ADS)

Maples, S.; Andraski, B. J.; Stonestrom, D. A.; Cooper, C. A.; Pohll, G.

2011-12-01

Studies at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS) in southern Nevada have documented long-distance (>400-m) tritium (3H) transport adjacent to a commercial, low-level radioactive waste disposal facility. Transport at this scale is orders of magnitude greater than anticipated; however, lateral 3H fluxes through the shallow unsaturated zone (UZ) have not been investigated in detail. The objective of this study is to estimate and compare lateral and vertical tritiated water-vapor (3HHOg) fluxes in the shallow UZ and their relation to the observed plume migration. Previous studies have recognized two distinct plumes of 3H emanating from the facility. Shallow (0.5 and 1.5-m depth) soil-water vapor samples were collected yearly along 400-m long transects through both plumes from 2003-09. Within the south plume, 3H concentrations at 1.5-m depth have decreased by 44 ± 0.3% during this period, and plume advancement there has effectively ceased (i.e., rate of advance equals rate of decay). During the same period, the west plume showed a net decrease in concentration of 34 ± 0.9% within 100-m of the facility; however, plume advancement is observed at the leading edge of the plume, and concentrations 200-300-m from the facility show an increase in 3H concentration of 64 ± 28.4%. Lateral and vertical diffusive fluxes within both plumes were calculated using 3HHOg concentrations from 2006. Lateral 3HHOg diffusive fluxes within both plumes have been estimated 25-300-m from the facility at 1.5-m depth. Mean lateral 3HHOg diffusive fluxes are 10-14 g m-2 yr-1 within the south plume, and 10-13 g m-2 yr-1 within the west plume. Mean lateral fluxes in the south plume are an order of magnitude lower than in the west plume. This behavior corresponds with the observed relative immobility of the south plume, while the elevated west plume fluxes agree with the plume advancement seen there. Shallow, upward directed, mean vertical 3HHOg fluxes 25-300-m from the facility are estimated to be 10-12 g m-2 yr-1 in the south plume and 10-11 g m-2 yr-1 in the west plume. Within both plumes, mean vertical diffusive fluxes are two orders of magnitude greater than mean lateral diffusive fluxes. Lateral diffusive 3HHOg fluxes have been calculated similarly using 2001 south plume data and were compared to 2001 south plume vertical diffusive 3HHOg fluxes published by Andraski et al. (2005). Here, too, mean vertical fluxes dwarf mean lateral fluxes (10-11 g m-2 yr-1 vs. 10-14 g m-2 yr-1). This behavior highlights the importance of upward movement and release of 3H to the atmosphere. The potential role of advective lateral transport and its contribution to observed plume migration is also under investigation.

Using multi-scale distribution and movement effects along a montane highway to identify optimal crossing locations for a large-bodied mammal community.

PubMed

Schuster, Richard; Römer, Heinrich; Germain, Ryan R

2013-01-01

Roads are a major cause of habitat fragmentation that can negatively affect many mammal populations. Mitigation measures such as crossing structures are a proposed method to reduce the negative effects of roads on wildlife, but the best methods for determining where such structures should be implemented, and how their effects might differ between species in mammal communities is largely unknown. We investigated the effects of a major highway through south-eastern British Columbia, Canada on several mammal species to determine how the highway may act as a barrier to animal movement, and how species may differ in their crossing-area preferences. We collected track data of eight mammal species across two winters, along both the highway and pre-marked transects, and used a multi-scale modeling approach to determine the scale at which habitat characteristics best predicted preferred crossing sites for each species. We found evidence for a severe barrier effect on all investigated species. Freely-available remotely-sensed habitat landscape data were better than more costly, manually-digitized microhabitat maps in supporting models that identified preferred crossing sites; however, models using both types of data were better yet. Further, in 6 of 8 cases models which incorporated multiple spatial scales were better at predicting preferred crossing sites than models utilizing any single scale. While each species differed in terms of the landscape variables associated with preferred/avoided crossing sites, we used a multi-model inference approach to identify locations along the highway where crossing structures may benefit all of the species considered. By specifically incorporating both highway and off-highway data and predictions we were able to show that landscape context plays an important role for maximizing mitigation measurement efficiency. Our results further highlight the need for mitigation measures along major highways to improve connectivity between mammal populations, and illustrate how multi-scale data can be used to identify preferred crossing sites for different species within a mammal community.

Infection Threshold for an Epidemic Model in Site and Bond Percolation Worlds

NASA Astrophysics Data System (ADS)

Sakisaka, Yukio; Yoshimura, Jin; Takeuchi, Yasuhiro; Sugiura, Koji; Tainaka, Kei-ichi

2010-02-01

We investigate an epidemic model on a square lattice with two protection treatments: prevention and quarantine. To explore the effects of both treatments, we apply the site and bond percolations. Computer simulations reveal that the threshold between endemic and disease-free phases can be represented by a single scaling law. The mean-field theory qualitatively predicts such infection dynamics and the scaling law.

Modification to Math Model for Small Independent Action Forces (SIAF)

DTIC Science & Technology

1973-12-15

counterdetection situations. 1 6905-6008-RO-00 Page 2-44 WOcc = &&ls-.4 ZI- Lw _ _ _c__ _ _ _c z I.- 1 0 & a dC n u4.3C w 4.3 4n4 WLU cs td .~ 1--AiI I.- .C uj w...i et. - - S - U , )UU U aIA ~ U tiu W WQ wi W W U w td - l l -i M iA .j CA -o *m *o mc mc fP6-133 󈨁 a~ Ac a S o- I N S ag I 9E 30. Q CY " a𔃻 aac...I- 4f ow060 0 OLCO0 wuCo; O ~"-j~ I UzAc 30 1bd 4 OW b D- 6- 4bd d fo 6 udOw od Ś.464 .4 d Ot 6- 64W 6 b*64t PaI 7-55 NiI II a j l! I 1/. a

Ocean Renewable Energy Research at U. New Hampshire

NASA Astrophysics Data System (ADS)

Wosnik, M.; Baldwin, K.; White, C.; Carter, M.; Gress, D.; Swift, R.; Tsukrov, I.; Kraft, G.; Celikkol, B.

2008-11-01

The University of New Hampshire (UNH) is strategically positioned to develop and evaluate wave and tidal energy extraction technologies, with much of the required test site infrastructure in place already. Laboratory facilities (wave/tow tanks, flumes, water tunnels) are used to test concept validation models (scale 1:25--100) and design models (scale 1:10--30). The UNH Open Ocean Aquaculture (OOA) site located 1.6 km south of the Isles of Shoals (10 km off shore) and the General Sullivan Bridge testing facility in the Great Bay Estuary are used to test process models (scale 1:3--15) and prototype/demonstration models (scale 1:1-- 4) of wave energy and tidal energy extraction devices, respectively. Both test sites are easily accessible and in close proximity of UNH, with off-the-shelf availability. The Great Bay Estuary system is one of the most energetic tidally driven estuaries on the East Coast of the U.S. The current at the General Sullivan bridge test facility reliably exceeds four knots over part of the tidal cycle. The OOA site is a ten year old, well established offshore test facility, and is continually serviced by a dedicated research vessel and operations/diving crew. In addition to an overview of the physical resources, results of recent field testing of half- and full-scale hydrokinetic turbines, and an analysis of recent acoustic Doppler surveys of the tidal estuary will be presented.

Assessment of the scale effect on statistical downscaling quality at a station scale using a weather generator-based model

USDA-ARS?s Scientific Manuscript database

The resolution of General Circulation Models (GCMs) is too coarse to assess the fine scale or site-specific impacts of climate change. Downscaling approaches including dynamical and statistical downscaling have been developed to meet this requirement. As the resolution of climate model increases, it...

Near infrared spectroscopy to estimate the temperature reached on burned soils: strategies to develop robust models.

NASA Astrophysics Data System (ADS)

Guerrero, César; Pedrosa, Elisabete T.; Pérez-Bejarano, Andrea; Keizer, Jan Jacob

2014-05-01

The temperature reached on soils is an important parameter needed to describe the wildfire effects. However, the methods for measure the temperature reached on burned soils have been poorly developed. Recently, the use of the near-infrared (NIR) spectroscopy has been pointed as a valuable tool for this purpose. The NIR spectrum of a soil sample contains information of the organic matter (quantity and quality), clay (quantity and quality), minerals (such as carbonates and iron oxides) and water contents. Some of these components are modified by the heat, and each temperature causes a group of changes, leaving a typical fingerprint on the NIR spectrum. This technique needs the use of a model (or calibration) where the changes in the NIR spectra are related with the temperature reached. For the development of the model, several aliquots are heated at known temperatures, and used as standards in the calibration set. This model offers the possibility to make estimations of the temperature reached on a burned sample from its NIR spectrum. However, the estimation of the temperature reached using NIR spectroscopy is due to changes in several components, and cannot be attributed to changes in a unique soil component. Thus, we can estimate the temperature reached by the interaction between temperature and the thermo-sensible soil components. In addition, we cannot expect the uniform distribution of these components, even at small scale. Consequently, the proportion of these soil components can vary spatially across the site. This variation will be present in the samples used to construct the model and also in the samples affected by the wildfire. Therefore, the strategies followed to develop robust models should be focused to manage this expected variation. In this work we compared the prediction accuracy of models constructed with different approaches. These approaches were designed to provide insights about how to distribute the efforts needed for the development of robust models, since this step is the bottle-neck of this technique. In the first approach, a plot-scale model was used to predict the temperature reached in samples collected in other plots from the same site. In a plot-scale model, all the heated aliquots come from a unique plot-scale sample. As expected, the results obtained with this approach were deceptive, because this approach was assuming that a plot-scale model would be enough to represent the whole variability of the site. The accuracy (measured as the root mean square error of prediction, thereinafter RMSEP) was 86ºC, and the bias was also high (>30ºC). In the second approach, the temperatures predicted through several plot-scale models were averaged. The accuracy was improved (RMSEP=65ºC) respect the first approach, because the variability from several plots was considered and biased predictions were partially counterbalanced. However, this approach implies more efforts, since several plot-scale models are needed. In the third approach, the predictions were obtained with site-scale models. These models were constructed with aliquots from several plots. In this case, the results were accurate, since the RMSEP was around 40ºC, the bias was very small (<1ºC) and the R2 was 0.92. As expected, this approach clearly outperformed the second approach, in spite of the fact that the same efforts were needed. In a plot-scale model, only one interaction between temperature and soil components was modelled. However, several different interactions between temperature and soil components were present in the calibration matrix of a site-scale model. Consequently, the site-scale models were able to model the temperature reached excluding the influence of the differences in soil composition, resulting in more robust models respect that variation. Summarizing, the results were highlighting the importance of an adequate strategy to develop robust and accurate models with moderate efforts, and how a wrong strategy can result in deceptive predictions.

Nested-scale discharge and groundwater level monitoring to improve predictions of flow route discharges and nitrate loads

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2010-10-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for predictions of catchment-scale discharge and nitrate loads. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate the groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements simulates better nitrate loads and better predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

Draft Genome Sequence of Candida pseudohaemulonii Isolated from the Blood of a Neutropenic Patient.

PubMed

Mohd Tap, Ratna; Kamarudin, Nur Amalina; Ginsapu, Stephanie Jane; Ahmed Bakri, Ahmed Rafezzan; Ahmad, Norazah; Amran, Fairuz; Sipiczki, Matthias

2018-04-05

Candida pseudohaemulonii is phylogenetically close to the C. haemulonii complex and exhibits resistance to amphotericin B and azole agents. We report here the draft genome sequence of C. pseudohaemulonii UZ153_17 isolated from the blood culture of a neutropenic patient. The draft genome is 3,532,003,666 bp in length, with 579,838 reads, 130 contigs, and a G+C content of 47.15%. Copyright © 2018 Mohd Tap et al.

Proceedings of the 13th Army Symposium on Solid Mechanics, 17-19 August 1993, Plymouth, Massachusetts.

DTIC Science & Technology

1993-01-01

the material relating the average stresses Ux(= Uz) to the eigenstrains e * is (Mallick and Krajcinovic, 1992a,b) 21 (yt)+ (p), 2 d-x(y, s) +R3 (y, s... eigenstrain in the material due to chemical shrinkage and thermal dilatation. During the chemical reaction of bonding two reacting monomers must reduce their...reaction (3) and connectivity dependent material properties and eigenstrains (4). However, the most prominent source of complexity is the fact that the

Corps of Engineers Structural Engineering Conference Held in St. Johns County, Florida on 8-12 July 1991. Volume 1

DTIC Science & Technology

1992-12-01

ville, surveying personnel and surveyors at fects from the concrete heat of hydration, the Engineering Technology Laboratory and solar radiation, and...CESEC91 Schuitz 317 LA-J 4 zz C.I.A 4 -r Lfl- ST. PEER ST 0’ Uz M 0; ~ w z d L 0l Fra lwý CLu V)C,0 W V) -j V- u0) 318r Bctjt CEE9 A304MC. PANAlS - ELE

A reduced-order modeling approach to represent subgrid-scale hydrological dynamics for land-surface simulations: application in a polygonal tundra landscape

DOE PAGES

Pau, G. S. H.; Bisht, G.; Riley, W. J.

2014-09-17

Existing land surface models (LSMs) describe physical and biological processes that occur over a wide range of spatial and temporal scales. For example, biogeochemical and hydrological processes responsible for carbon (CO 2, CH 4) exchanges with the atmosphere range from the molecular scale (pore-scale O 2 consumption) to tens of kilometers (vegetation distribution, river networks). Additionally, many processes within LSMs are nonlinearly coupled (e.g., methane production and soil moisture dynamics), and therefore simple linear upscaling techniques can result in large prediction error. In this paper we applied a reduced-order modeling (ROM) technique known as "proper orthogonal decomposition mapping method" thatmore » reconstructs temporally resolved fine-resolution solutions based on coarse-resolution solutions. We developed four different methods and applied them to four study sites in a polygonal tundra landscape near Barrow, Alaska. Coupled surface–subsurface isothermal simulations were performed for summer months (June–September) at fine (0.25 m) and coarse (8 m) horizontal resolutions. We used simulation results from three summer seasons (1998–2000) to build ROMs of the 4-D soil moisture field for the study sites individually (single-site) and aggregated (multi-site). The results indicate that the ROM produced a significant computational speedup (> 10 3) with very small relative approximation error (< 0.1%) for 2 validation years not used in training the ROM. We also demonstrate that our approach: (1) efficiently corrects for coarse-resolution model bias and (2) can be used for polygonal tundra sites not included in the training data set with relatively good accuracy (< 1.7% relative error), thereby allowing for the possibility of applying these ROMs across a much larger landscape. By coupling the ROMs constructed at different scales together hierarchically, this method has the potential to efficiently increase the resolution of land models for coupled climate simulations to spatial scales consistent with mechanistic physical process representation.« less

Project M: Scale Model of Lunar Landing Site of Apollo 17: Focus on Lighting Conditions and Analysis

NASA Technical Reports Server (NTRS)

Vanik, Christopher S.; Crain, Timothy P.

2010-01-01

This document captures the research and development of a scale model representation of the Apollo 17 landing site on the moon as part of the NASA INSPIRE program. Several key elements in this model were surface slope characteristics, crater sizes and locations, prominent rocks, and lighting conditions. This model supports development of Autonomous Landing and Hazard Avoidance Technology (ALHAT) and Project M for the GN&C Autonomous Flight Systems Branch. It will help project engineers visualize the landing site, and is housed in the building 16 Navigation Systems Technology Lab. The lead mentor was Dr. Timothy P. Crain. The purpose of this project was to develop an accurate scale representation of the Apollo 17 landing site on the moon. This was done on an 8'2.5"X10'1.375" reduced friction granite table, which can be restored to its previous condition if needed. The first step in this project was to research the best way to model and recreate the Apollo 17 landing site for the mockup. The project required a thorough plan, budget, and schedule, which was presented to the EG6 Branch for build approval. The final phase was to build the model. The project also required thorough research on the Apollo 17 landing site and the topography of the moon. This research was done on the internet and in person with Dean Eppler, a space scientist, from JSC KX. This data was used to analyze and calculate the scale of the mockup and the ratio of the sizes of the craters, ridges, etc. The final goal was to effectively communicate project status and demonstrate the multiple advantages of using our model. The conclusion of this project was that the mockup was completed as accurately as possible, and it successfully enables the Project M specialists to visualize and plan their goal on an accurate three dimensional surface representation.

The role of fanatics in consensus formation

NASA Astrophysics Data System (ADS)

Gündüç, Semra

2015-08-01

A model of opinion dynamics with two types of agents as social actors are presented, using the Ising thermodynamic model as the dynamics template. The agents are considered as opportunists which live at sites and interact with the neighbors, or fanatics/missionaries which move from site to site randomly in persuasion of converting agents of opposite opinion with the help of opportunists. Here, the moving agents act as an external influence on the opportunists to convert them to the opposite opinion. It is shown by numerical simulations that such dynamics of opinion formation may explain some details of consensus formation even when one of the opinions are held by a minority. Regardless the distribution of the opinion, different size societies exhibit different opinion formation behavior and time scales. In order to understand general behavior, the scaling relations obtained by comparing opinion formation processes observed in societies with varying population and number of randomly moving agents are studied. For the proposed model two types of scaling relations are observed. In fixed size societies, increasing the number of randomly moving agents give a scaling relation for the time scale of the opinion formation process. The second type of scaling relation is due to the size dependent information propagation in finite but large systems, namely finite-size scaling.

Multi-scale groundwater flow modeling during temperate climate conditions for the safety assessment of the proposed high-level nuclear waste repository site at Forsmark, Sweden

NASA Astrophysics Data System (ADS)

Joyce, Steven; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter

2014-09-01

Forsmark in Sweden has been proposed as the site of a geological repository for spent high-level nuclear fuel, to be located at a depth of approximately 470 m in fractured crystalline rock. The safety assessment for the repository has required a multi-disciplinary approach to evaluate the impact of hydrogeological and hydrogeochemical conditions close to the repository and in a wider regional context. Assessing the consequences of potential radionuclide releases requires quantitative site-specific information concerning the details of groundwater flow on the scale of individual waste canister locations (1-10 m) as well as details of groundwater flow and composition on the scale of groundwater pathways between the facility and the surface (500 m to 5 km). The purpose of this article is to provide an illustration of multi-scale modeling techniques and the results obtained when combining aspects of local-scale flows in fractures around a potential contaminant source with regional-scale groundwater flow and transport subject to natural evolution of the system. The approach set out is novel, as it incorporates both different scales of model and different levels of detail, combining discrete fracture network and equivalent continuous porous medium representations of fractured bedrock.

Insights for empirically modeling evapotranspiration influenced by riparian and upland vegetation in semiarid regions

USGS Publications Warehouse

Bunting, Daniel P.; Kurc, Shirley A.; Glenn, Edward P.; Nagler, Pamela L.; Scott, Russell L.

2014-01-01

Water resource managers aim to ensure long-term water supplies for increasing human populations. Evapotranspiration (ET) is a key component of the water balance and accurate estimates are important to quantify safe allocations to humans while supporting environmental needs. Scaling up ET measurements from small spatial scales has been problematic due to spatiotemporal variability. Remote sensing products provide spatially distributed data that account for seasonal climate and vegetation variability. We used MODIS products [i.e., Enhanced Vegetation Index (EVI) and nighttime land surface temperatures (LSTn)] to create empirical ET models calibrated using measured ET from three riparian-influenced and two upland, water-limited flux tower sites. Results showed that combining all sites introduced systematic bias, so we developed separate models to estimate riparian and upland ET. While EVI and LSTn were the main drivers for ET in riparian sites, precipitation replaced LSTn as the secondary driver of ET in upland sites. Riparian ET was successfully modeled using an inverse exponential approach (r2 = 0.92) while upland ET was adequately modeled using a multiple linear regression approach (r2 = 0.77). These models can be used in combination to estimate ET at basin scales provided each region is classified and precipitation data is available.

Landscape-and regional-scale shifts in forest composition under climate change in the Central Hardwood Region of the United States

Treesearch

Wen J. Wang; Hong S. He; Frank R. Thompson; Jacob S. Fraser; William D. Dijak

2016-01-01

Tree species distribution and abundance are affected by forces operating at multiple scales. Niche and biophysical process models have been commonly used to predict climate change effects at regional scales, however, these models have limited capability to include site-scale population dynamics and landscape- scale disturbance and dispersal. We applied a landscape...

WIND-TUNNEL SIMULATIONS TO ASSESS DISPERSION AROUND THE WORLD TRADE CENTER SITE

EPA Science Inventory

A wind-tunnel study was conducted of dispersion from the site of the destroyed World Trade Center (WTC) in New York City. A scale model of lower Manhattan, including a scaled representation of the rubble pile, was constructed. The first phases of the study involved smoke visua...

GIS-based rapid-assessment of bighead carp Hypophthalmichthys nobilis (Richardson, 1845) suitability in reservoirs

USGS Publications Warehouse

Long, James M.; Liang, Yu; Shoup, Daniel E.; Dzialowski, Andrew R.; Bidwell, Joseph R.

2014-01-01

Broad-scale niche models are good for examining the potential for invasive species occurrences, but can fall short in providing managers with site-specific locations for monitoring. Using Oklahoma as an example, where invasive bighead carp (Hypophthalmichthys nobilis) are established in certain reservoirs, but predicted to be widely distributed based on broad-scale niche models, we cast bighead carp reproductive ecology in a site-specific geospatial framework to determine their potential establishment in additional reservoirs. Because bighead carp require large, long free-flowing rivers with suitable hydrology for reproduction but can persist in reservoirs, we considered reservoir tributaries with mean annual daily discharge ≥8.5 cubic meters per second (m3 /s) and quantified the length of their unimpeded portions. In contrast to published broad-scale niche models that identified nearly the entire state as susceptible to invasion, our site-specific models showed that few reservoirs in Oklahoma (N = 9) were suitable for bighead carp establishment. Moreover, this method was rapid and identified sites that could be prioritized for increased study or scrutiny. Our results highlight the importance of considering the environmental characteristics of individual sites, which is often the level at which management efforts are implemented when assessing susceptibility to invasion.

Characteristics of HIV Care and Treatment in PEPFAR-Supported Sites

PubMed Central

Filler, Scott; Berruti, Andres A.; Menzies, Nick; Berzon, Rick; Ellerbrock, Tedd V.; Ferris, Robert; Blandford, John M.

2011-01-01

Background The U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) has supported the extension of HIV care and treatment to 2.4 million individuals by September 2009. With increasing resources targeted toward scale-up, it is important to understand the characteristics of current PEPFAR-supported HIV care and treatment sites. Methods Forty-five sites in Botswana, Ethiopia, Nigeria, Uganda, and Vietnam were sampled. Data were collected retrospectively from successive 6-month periods of site operations, through reviews of facility records and interviews with site personnel between April 2006 and March 2007. Facility size and scale-up rate, patient characteristics, staffing models, clinical and laboratory monitoring, and intervention mix were compared. Results Sites added a median of 293 patients per quarter. By the evaluation’s end, sites supported a median of 1,649 HIV patients, 922 of them receiving antiretroviral therapy (ART). Patients were predominantly adult (97.4%) and the majority (96.5%) were receiving regimens based on nonnucleoside reverse transcriptase inhibitors (NNRTIs). The ratios of physicians to patients dropped substantially as sites matured. ART patients were commonly seen monthly or quarterly for clinical and laboratory monitoring, with CD4 counts being taken at 6-month intervals. One-third of sites provided viral load testing. Cotrimoxazole prophylaxis was the most prevalent supportive service. Conclusions HIV treatment sites scaled up rapidly with the influx of resources and technical support through PEPFAR, providing complex health services to progressively expanding patient cohorts. Human resources are stretched thin, and delivery models and intervention mix differ widely between sites. Ongoing research is needed to identify best-practice service delivery models. PMID:21346585

A New Scheme to Characterize and Identify Protein Ubiquitination Sites.

PubMed

Nguyen, Van-Nui; Huang, Kai-Yao; Huang, Chien-Hsun; Lai, K Robert; Lee, Tzong-Yi

2017-01-01

Protein ubiquitination, involving the conjugation of ubiquitin on lysine residue, serves as an important modulator of many cellular functions in eukaryotes. Recent advancements in proteomic technology have stimulated increasing interest in identifying ubiquitination sites. However, most computational tools for predicting ubiquitination sites are focused on small-scale data. With an increasing number of experimentally verified ubiquitination sites, we were motivated to design a predictive model for identifying lysine ubiquitination sites for large-scale proteome dataset. This work assessed not only single features, such as amino acid composition (AAC), amino acid pair composition (AAPC) and evolutionary information, but also the effectiveness of incorporating two or more features into a hybrid approach to model construction. The support vector machine (SVM) was applied to generate the prediction models for ubiquitination site identification. Evaluation by five-fold cross-validation showed that the SVM models learned from the combination of hybrid features delivered a better prediction performance. Additionally, a motif discovery tool, MDDLogo, was adopted to characterize the potential substrate motifs of ubiquitination sites. The SVM models integrating the MDDLogo-identified substrate motifs could yield an average accuracy of 68.70 percent. Furthermore, the independent testing result showed that the MDDLogo-clustered SVM models could provide a promising accuracy (78.50 percent) and perform better than other prediction tools. Two cases have demonstrated the effective prediction of ubiquitination sites with corresponding substrate motifs.

Integrating ecosystems measurements from multiple eddy-covariance sites to a simple model of ecosystem process - Are there possibilities for a uniform model calibration?

NASA Astrophysics Data System (ADS)

Minunno, Francesco; Peltoniemi, Mikko; Launiainen, Samuli; Mäkelä, Annikki

2014-05-01

Biogeochemical models quantify the material and energy flux exchanges between biosphere, atmosphere and soil, however there is still considerable uncertainty underpinning model structure and parametrization. The increasing availability of data from of multiple sources provides useful information for model calibration and validation at different space and time scales. We calibrated a simplified ecosystem process model PRELES to data from multiple sites. In this work we had the following objective: to compare a multi-site calibration and site-specific calibrations, in order to test if PRELES is a model of general applicability, and to test how well one parameterization can predict ecosystem fluxes. Model calibration and evaluation were carried out by the means of the Bayesian method; Bayesian calibration (BC) and Bayesian model comparison (BMC) were used to quantify the uncertainty in model parameters and model structure. Evapotranspiration (ET) and gross primary production (GPP) measurements collected in 9 sites of Finland and Sweden were used in the study; half dataset was used for model calibrations and half for the comparative analyses. 10 BCs were performed; the model was independently calibrated for each of the nine sites (site-specific calibrations) and a multi-site calibration was achieved using the data from all the sites in one BC. Then 9 BMCs were carried out, one for each site, using output from the multi-site and the site-specific versions of PRELES. Similar estimates were obtained for the parameters at which model outputs are most sensitive. Not surprisingly, the joint posterior distribution achieved through the multi-site calibration was characterized by lower uncertainty, because more data were involved in the calibration process. No significant differences were encountered in the prediction of the multi-site and site-specific versions of PRELES, and after BMC, we concluded that the model can be reliably used at regional scale to simulate carbon and water fluxes of Boreal forests. Despite being a simple model, PRELES provided good estimates of GPP and ET; only for one site PRELES multi-site version underestimated water fluxes. Our study implies convergence of GPP and water processes in boreal zone to the extent that their plausible prediction is possible with a simple model using global parameterization.

Using multi-scale distribution and movement effects along a montane highway to identify optimal crossing locations for a large-bodied mammal community

PubMed Central

Römer, Heinrich; Germain, Ryan R.

2013-01-01

Roads are a major cause of habitat fragmentation that can negatively affect many mammal populations. Mitigation measures such as crossing structures are a proposed method to reduce the negative effects of roads on wildlife, but the best methods for determining where such structures should be implemented, and how their effects might differ between species in mammal communities is largely unknown. We investigated the effects of a major highway through south-eastern British Columbia, Canada on several mammal species to determine how the highway may act as a barrier to animal movement, and how species may differ in their crossing-area preferences. We collected track data of eight mammal species across two winters, along both the highway and pre-marked transects, and used a multi-scale modeling approach to determine the scale at which habitat characteristics best predicted preferred crossing sites for each species. We found evidence for a severe barrier effect on all investigated species. Freely-available remotely-sensed habitat landscape data were better than more costly, manually-digitized microhabitat maps in supporting models that identified preferred crossing sites; however, models using both types of data were better yet. Further, in 6 of 8 cases models which incorporated multiple spatial scales were better at predicting preferred crossing sites than models utilizing any single scale. While each species differed in terms of the landscape variables associated with preferred/avoided crossing sites, we used a multi-model inference approach to identify locations along the highway where crossing structures may benefit all of the species considered. By specifically incorporating both highway and off-highway data and predictions we were able to show that landscape context plays an important role for maximizing mitigation measurement efficiency. Our results further highlight the need for mitigation measures along major highways to improve connectivity between mammal populations, and illustrate how multi-scale data can be used to identify preferred crossing sites for different species within a mammal community. PMID:24244912

A test of the hierarchical model of litter decomposition.

PubMed

Bradford, Mark A; Veen, G F Ciska; Bonis, Anne; Bradford, Ella M; Classen, Aimee T; Cornelissen, J Hans C; Crowther, Thomas W; De Long, Jonathan R; Freschet, Gregoire T; Kardol, Paul; Manrubia-Freixa, Marta; Maynard, Daniel S; Newman, Gregory S; Logtestijn, Richard S P; Viketoft, Maria; Wardle, David A; Wieder, William R; Wood, Stephen A; van der Putten, Wim H

2017-12-01

Our basic understanding of plant litter decomposition informs the assumptions underlying widely applied soil biogeochemical models, including those embedded in Earth system models. Confidence in projected carbon cycle-climate feedbacks therefore depends on accurate knowledge about the controls regulating the rate at which plant biomass is decomposed into products such as CO 2 . Here we test underlying assumptions of the dominant conceptual model of litter decomposition. The model posits that a primary control on the rate of decomposition at regional to global scales is climate (temperature and moisture), with the controlling effects of decomposers negligible at such broad spatial scales. Using a regional-scale litter decomposition experiment at six sites spanning from northern Sweden to southern France-and capturing both within and among site variation in putative controls-we find that contrary to predictions from the hierarchical model, decomposer (microbial) biomass strongly regulates decomposition at regional scales. Furthermore, the size of the microbial biomass dictates the absolute change in decomposition rates with changing climate variables. Our findings suggest the need for revision of the hierarchical model, with decomposers acting as both local- and broad-scale controls on litter decomposition rates, necessitating their explicit consideration in global biogeochemical models.

The Lévy flight foraging hypothesis: forgetting about memory may lead to false verification of Brownian motion.

PubMed

Gautestad, Arild O; Mysterud, Atle

2013-01-01

The Lévy flight foraging hypothesis predicts a transition from scale-free Lévy walk (LW) to scale-specific Brownian motion (BM) as an animal moves from resource-poor towards resource-rich environment. However, the LW-BM continuum implies a premise of memory-less search, which contradicts the cognitive capacity of vertebrates. We describe methods to test if apparent support for LW-BM transitions may rather be a statistical artifact from movement under varying intensity of site fidelity. A higher frequency of returns to previously visited patches (stronger site fidelity) may erroneously be interpreted as a switch from LW towards BM. Simulations of scale-free, memory-enhanced space use illustrate how the ratio between return events and scale-free exploratory movement translates to varying strength of site fidelity. An expanded analysis of GPS data of 18 female red deer, Cervus elaphus, strengthens previous empirical support of memory-enhanced and scale-free space use in a northern forest ecosystem. A statistical mechanical model architecture that describes foraging under environment-dependent variation of site fidelity may allow for higher realism of optimal search models and movement ecology in general, in particular for vertebrates with high cognitive capacity.

Damping scaling factors for elastic response spectra for shallow crustal earthquakes in active tectonic regions: "average" horizontal component

USGS Publications Warehouse

Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Abrahamson, Norman; Campbell, Kenneth; Silva, Walter

2014-01-01

Ground motion prediction equations (GMPEs) for elastic response spectra are typically developed at a 5% viscous damping ratio. In reality, however, structural and nonstructural systems can have other damping ratios. This paper develops a new model for a damping scaling factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE for damping ratios between 0.5% to 30%. The model is developed based on empirical data from worldwide shallow crustal earthquakes in active tectonic regions. Dependencies of the DSF on potential predictor variables, such as the damping ratio, spectral period, ground motion duration, moment magnitude, source-to-site distance, and site conditions, are examined. The strong influence of duration is captured by the inclusion of both magnitude and distance in the DSF model. Site conditions show weak influence on the DSF. The proposed damping scaling model provides functional forms for the median and logarithmic standard deviation of DSF, and is developed for both RotD50 and GMRotI50 horizontal components. A follow-up paper develops a DSF model for vertical ground motion.

Sustainability of High Intensity Forest Management with Respect to Water QuaIity and Site Nutrient Reserves

Treesearch

Virginia R. Tolbert; Carl C. Trettin; Dale W. Johnson; John W. Parsons; Allan E. Houston; David A. Mays

2001-01-01

Ensuring sustainability of intensively managed woody crops requires determining soil and water quality effects using a combination of field data and modeling projections. Plot- and catchrnent-scale research, models, and meta-analyses are addressing nutrient availability, site quality, and measures to increase short-rotation woody crop (SRWC) productivity and site...

Cross-site comparison of land-use decision-making and its consequences across land systems with a generalized agent-based model.

PubMed

Magliocca, Nicholas R; Brown, Daniel G; Ellis, Erle C

2014-01-01

Local changes in land use result from the decisions and actions of land-users within land systems, which are structured by local and global environmental, economic, political, and cultural contexts. Such cross-scale causation presents a major challenge for developing a general understanding of how local decision-making shapes land-use changes at the global scale. This paper implements a generalized agent-based model (ABM) as a virtual laboratory to explore how global and local processes influence the land-use and livelihood decisions of local land-users, operationalized as settlement-level agents, across the landscapes of six real-world test sites. Test sites were chosen in USA, Laos, and China to capture globally-significant variation in population density, market influence, and environmental conditions, with land systems ranging from swidden to commercial agriculture. Publicly available global data were integrated into the ABM to model cross-scale effects of economic globalization on local land-use decisions. A suite of statistics was developed to assess the accuracy of model-predicted land-use outcomes relative to observed and random (i.e. null model) landscapes. At four of six sites, where environmental and demographic forces were important constraints on land-use choices, modeled land-use outcomes were more similar to those observed across sites than the null model. At the two sites in which market forces significantly influenced land-use and livelihood decisions, the model was a poorer predictor of land-use outcomes than the null model. Model successes and failures in simulating real-world land-use patterns enabled the testing of hypotheses on land-use decision-making and yielded insights on the importance of missing mechanisms. The virtual laboratory approach provides a practical framework for systematic improvement of both theory and predictive skill in land change science based on a continual process of experimentation and model enhancement.

Cross-Site Comparison of Land-Use Decision-Making and Its Consequences across Land Systems with a Generalized Agent-Based Model

PubMed Central

Magliocca, Nicholas R.; Brown, Daniel G.; Ellis, Erle C.

2014-01-01

Local changes in land use result from the decisions and actions of land-users within land systems, which are structured by local and global environmental, economic, political, and cultural contexts. Such cross-scale causation presents a major challenge for developing a general understanding of how local decision-making shapes land-use changes at the global scale. This paper implements a generalized agent-based model (ABM) as a virtual laboratory to explore how global and local processes influence the land-use and livelihood decisions of local land-users, operationalized as settlement-level agents, across the landscapes of six real-world test sites. Test sites were chosen in USA, Laos, and China to capture globally-significant variation in population density, market influence, and environmental conditions, with land systems ranging from swidden to commercial agriculture. Publicly available global data were integrated into the ABM to model cross-scale effects of economic globalization on local land-use decisions. A suite of statistics was developed to assess the accuracy of model-predicted land-use outcomes relative to observed and random (i.e. null model) landscapes. At four of six sites, where environmental and demographic forces were important constraints on land-use choices, modeled land-use outcomes were more similar to those observed across sites than the null model. At the two sites in which market forces significantly influenced land-use and livelihood decisions, the model was a poorer predictor of land-use outcomes than the null model. Model successes and failures in simulating real-world land-use patterns enabled the testing of hypotheses on land-use decision-making and yielded insights on the importance of missing mechanisms. The virtual laboratory approach provides a practical framework for systematic improvement of both theory and predictive skill in land change science based on a continual process of experimentation and model enhancement. PMID:24489696

Strategy for long-term 3D cloud-resolving simulations over the ARM SGP site and preliminary results

NASA Astrophysics Data System (ADS)

Lin, W.; Liu, Y.; Song, H.; Endo, S.

2011-12-01

Parametric representations of cloud/precipitation processes continue having to be adopted in climate simulations with increasingly higher spatial resolution or with emerging adaptive mesh framework; and it is only becoming more critical that such parameterizations have to be scale aware. Continuous cloud measurements at DOE's ARM sites have provided a strong observational basis for novel cloud parameterization research at various scales. Despite significant progress in our observational ability, there are important cloud-scale physical and dynamical quantities that are either not currently observable or insufficiently sampled. To complement the long-term ARM measurements, we have explored an optimal strategy to carry out long-term 3-D cloud-resolving simulations over the ARM SGP site using Weather Research and Forecasting (WRF) model with multi-domain nesting. The factors that are considered to have important influences on the simulated cloud fields include domain size, spatial resolution, model top, forcing data set, model physics and the growth of model errors. The hydrometeor advection that may play a significant role in hydrological process within the observational domain but is often lacking, and the limitations due to the constraint of domain-wide uniform forcing in conventional cloud system-resolving model simulations, are at least partly accounted for in our approach. Conventional and probabilistic verification approaches are employed first for selected cases to optimize the model's capability of faithfully reproducing the observed mean and statistical distributions of cloud-scale quantities. This then forms the basis of our setup for long-term cloud-resolving simulations over the ARM SGP site. The model results will facilitate parameterization research, as well as understanding and dissecting parameterization deficiencies in climate models.

Characterizing the performance of ecosystem models across time scales: A spectral analysis of the North American Carbon Program site-level synthesis

Treesearch

Michael C. Dietze; Rodrigo Vargas; Andrew D. Richardson; Paul C. Stoy; Alan G. Barr; Ryan S. Anderson; M. Altaf Arain; Ian T. Baker; T. Andrew Black; Jing M. Chen; Philippe Ciais; Lawrence B. Flanagan; Christopher M. Gough; Robert F. Grant; David Hollinger; R. Cesar Izaurralde; Christopher J. Kucharik; Peter Lafleur; Shugang Liu; Erandathie Lokupitiya; Yiqi Luo; J. William Munger; Changhui Peng; Benjamin Poulter; David T. Price; Daniel M. Ricciuto; William J. Riley; Alok Kumar Sahoo; Kevin Schaefer; Andrew E. Suyker; Hanqin Tian; Christina Tonitto; Hans Verbeeck; Shashi B. Verma; Weifeng Wang; Ensheng Weng

2011-01-01

Ecosystem models are important tools for diagnosing the carbon cycle and projecting its behavior across space and time. Despite the fact that ecosystems respond to drivers at multiple time scales, most assessments of model performance do not discriminate different time scales. Spectral methods, such as wavelet analyses, present an alternative approach that enables the...

Crucial nesting habitat for gunnison sage-grouse: A spatially explicit hierarchical approach

USGS Publications Warehouse

Aldridge, Cameron L.; Saher, D.J.; Childers, T.M.; Stahlnecker, K.E.; Bowen, Z.H.

2012-01-01

Gunnison sage-grouse (Centrocercus minimus) is a species of special concern and is currently considered a candidate species under Endangered Species Act. Careful management is therefore required to ensure that suitable habitat is maintained, particularly because much of the species' current distribution is faced with exurban development pressures. We assessed hierarchical nest site selection patterns of Gunnison sage-grouse inhabiting the western portion of the Gunnison Basin, Colorado, USA, at multiple spatial scales, using logistic regression-based resource selection functions. Models were selected using Akaike Information Criterion corrected for small sample sizes (AIC c) and predictive surfaces were generated using model averaged relative probabilities. Landscape-scale factors that had the most influence on nest site selection included the proportion of sagebrush cover >5%, mean productivity, and density of 2 wheel-drive roads. The landscape-scale predictive surface captured 97% of known Gunnison sage-grouse nests within the top 5 of 10 prediction bins, implicating 57% of the basin as crucial nesting habitat. Crucial habitat identified by the landscape model was used to define the extent for patch-scale modeling efforts. Patch-scale variables that had the greatest influence on nest site selection were the proportion of big sagebrush cover >10%, distance to residential development, distance to high volume paved roads, and mean productivity. This model accurately predicted independent nest locations. The unique hierarchical structure of our models more accurately captures the nested nature of habitat selection, and allowed for increased discrimination within larger landscapes of suitable habitat. We extrapolated the landscape-scale model to the entire Gunnison Basin because of conservation concerns for this species. We believe this predictive surface is a valuable tool which can be incorporated into land use and conservation planning as well the assessment of future land-use scenarios. ?? 2011 The Wildlife Society.

Investigating the Macrodispersion Experiment (MADE) site in Columbus, Mississippi, using a three‐dimensional inverse flow and transport model

USGS Publications Warehouse

Christiansen Barlebo , Heidi; Hill, Mary C.; Rosbjerg, Dan

2004-01-01

Flowmeter‐measured hydraulic conductivities from the heterogeneous MADE site have been used predictively in advection‐dispersion models. Resulting simulated concentrations failed to reproduce even major plume characteristics and some have concluded that other mechanisms, such as dual porosity, are important. Here an alternative possibility is investigated: that the small‐scale flowmeter measurements are too noisy and possibly too biased to use so directly in site‐scale models and that the hydraulic head and transport data are more suitable for site‐scale characterization. Using a calibrated finite element model of the site and a new framework to evaluate random and systematic model and measurement errors, the following conclusions are derived. (1) If variations in subsurface fluid velocities like those simulated in this work (0.1 and 2.0 m per day along parallel and reasonably close flow paths) exist, it is likely that classical advection‐dispersion processes can explain the measured plume characteristics. (2) The flowmeter measurements are possibly systematically lower than site‐scale values when the measurements are considered individually and using common averaging methods and display variability that obscures abrupt changes in hydraulic conductivities that are well supported by changes in hydraulic gradients and are important to the simulation of transport.

Productivity benefits of warming at regional scale could be offset by detrimental impacts on site level hydrology.

PubMed

Zeng, Qing; Zhang, Yamian; Wen, Li; Li, Zhaxijie; Duo, Hairui; Lei, Guangchun

2017-11-09

Climate change affects the distribution and persistence of wildlife. Broad scale studies have demonstrated that climate change shifts the geographic ranges and phenology of species. These findings are influential for making high level strategies but not practical enough to guide site specific management. In this study, we explored the environment factors affecting the population of Bar-headed Goose in the key breeding site of Qinghai using generalized additive mixed model (GAMM). Our results showed that 1) there were significant increasing trends in climate variables and river flows to the Qinghai Lake; 2) NDVI in the sites decreased significantly despite the regional positive trend induced by the warmer and wetter climate; 3) NDVI at site scale was negatively correlated to lake water level; and 4) the abundance of Bar-headed Goose decreased significantly at all sites. While the abundance was positively related to NDVI at breeding sites, the GAMM revealed an opposite relationship at foraging areas. Our findings demonstrated the multi-facet effects of climate change on population dynamics; and the effect at global/regional scale could be complicated by site level factors.

Missing Data and Influential Sites: Choice of Sites for Phylogenetic Analysis Can Be As Important As Taxon Sampling and Model Choice

PubMed Central

Shavit Grievink, Liat; Penny, David; Holland, Barbara R.

2013-01-01

Phylogenetic studies based on molecular sequence alignments are expected to become more accurate as the number of sites in the alignments increases. With the advent of genomic-scale data, where alignments have very large numbers of sites, bootstrap values close to 100% and posterior probabilities close to 1 are the norm, suggesting that the number of sites is now seldom a limiting factor on phylogenetic accuracy. This provokes the question, should we be fussy about the sites we choose to include in a genomic-scale phylogenetic analysis? If some sites contain missing data, ambiguous character states, or gaps, then why not just throw them away before conducting the phylogenetic analysis? Indeed, this is exactly the approach taken in many phylogenetic studies. Here, we present an example where the decision on how to treat sites with missing data is of equal importance to decisions on taxon sampling and model choice, and we introduce a graphical method for illustrating this. PMID:23471508

Hydrological and geomorphological controls of malaria transmission

NASA Astrophysics Data System (ADS)

Smith, M. W.; Macklin, M. G.; Thomas, C. J.

2013-01-01

Malaria risk is linked inextricably to the hydrological and geomorphological processes that form vector breeding sites. Yet environmental controls of malaria transmission are often represented by temperature and rainfall amounts, ignoring hydrological and geomorphological influences altogether. Continental-scale studies incorporate hydrology implicitly through simple minimum rainfall thresholds, while community-scale coupled hydrological and entomological models do not represent the actual diversity of the mosquito vector breeding sites. The greatest range of malaria transmission responses to environmental factors is observed at the catchment scale where seemingly contradictory associations between rainfall and malaria risk can be explained by hydrological and geomorphological processes that govern surface water body formation and persistence. This paper extends recent efforts to incorporate ecological factors into malaria-risk models, proposing that the same detailed representation be afforded to hydrological and, at longer timescales relevant for predictions of climate change impacts, geomorphological processes. We review existing representations of environmental controls of malaria and identify a range of hydrologically distinct vector breeding sites from existing literature. We illustrate the potential complexity of interactions among hydrology, geomorphology and vector breeding sites by classifying a range of water bodies observed in a catchment in East Africa. Crucially, the mechanisms driving surface water body formation and destruction must be considered explicitly if we are to produce dynamic spatial models of malaria risk at catchment scales.

Predictors of breeding site occupancy by amphibians in montane landscapes

USGS Publications Warehouse

Groff, Luke A.; Loftin, Cynthia S.; Calhoun, Aram J.K.

2017-01-01

Ecological relationships and processes vary across species’ geographic distributions, life stages and spatial, and temporal scales. Montane landscapes are characterized by low wetland densities, rugged topographies, and cold climates. Consequently, aquatic-dependent and low-vagility ectothermic species (e.g., pool-breeding amphibians) may exhibit unique ecological associations in montane landscapes. We evaluated the relative importance of breeding- and landscape-scale features associated with spotted salamander (Ambystoma maculatum) and wood frog (Lithobates sylvaticus) wetland occupancy in Maine's Upper Montane-Alpine Zone ecoregion, and we determined whether models performed better when the inclusive landscape-scale covariates were estimated with topography-weighted or circular buffers. We surveyed 135 potential breeding sites during May 2013–June 2014 and evaluated environmental relationships with multi-season implicit dynamics occupancy models. Breeding site occupancy by both species was influenced solely by breeding-scale habitat features. Spotted salamander occupancy probabilities increased with previous or current beaver (Castor canadensis) presence, and models generally were better supported when the inclusive landscape-scale covariates were estimated with topography-weighted rather than circular buffers. Wood frog occupancy probabilities increased with site area and percent shallows, but neither buffer type was better supported than the other. Model rank order and support varied between buffer types, but model inferences did not. Our results suggest pool-breeding amphibian conservation in montane Maine include measures to maintain beaver populations and large wetlands with proportionally large areas of shallows ≤1-m deep. Inconsistencies between our study and previous studies substantiate the value of region-specific research for augmenting species’ conservation management plans and suggest the application of out-of-region inferences may promote ineffective conservation. 

Comparison of unmanned aircraft systems (UAS) to LiDAR for streambank erosion measurement at the site-specific and river network scales

NASA Astrophysics Data System (ADS)

Hamshaw, S. D.; Dewoolkar, M. M.; Rizzo, D.; ONeil-Dunne, J.; Frolik, J.

2016-12-01

Measurement of rates and extent of streambank erosion along river corridors is an important component of many catchment studies and necessary for engineering projects such as river restoration, hazard assessment, and total maximum daily load (TMDL) development. A variety of methods have been developed to quantify streambank erosion, including bank pins, ground surveys, photogrammetry, LiDAR, and analytical models. However, these methods are not only resource intensive, but many are feasible and appropriate only for site-specific studies and not practical for erosion estimates at larger scales. Recent advancements in unmanned aircraft systems (UAS) and photogrammetry software provide capabilities for more rapid and economical quantification of streambank erosion and deposition at multiple scales (from site-specific to river network). At the site-specific scale, the capability of UAS to quantify streambank erosion was compared to terrestrial laser scanning (TLS) and RTK-GPS ground survey and assessed at seven streambank monitoring sites in central Vermont. Across all sites, the UAS-derived bank topography had mean errors of 0.21 m compared to TLS and GPS data. Highest accuracies were achieved in early spring conditions where mean errors approached 10 cm. The cross sectional area of bank erosion at a typical, vegetated streambank site was found to be reliably calculated within 10% of actual for erosion areas greater than 3.5 m2. At the river network-level scale, 20 km of river corridor along the New Haven, Winooski, and Mad Rivers was flown on multiple dates with UAS and used to generate digital elevation models (DEMs) that were then compared for change detection analysis. Airborne LiDAR data collected prior to UAS surveys was also compared to UAS data to determine multi-year rates of bank erosion. UAS-based photogrammetry for generation of fine scale topographic data shows promise for the monitoring of streambank erosion both at the individual site scale and river-network scale in areas that are not densely covered with vegetation year-round.

Linking Meteorology, Air Quality Models and Observations to ...

EPA Pesticide Factsheets

Epidemiologic studies are critical in establishing the association between exposure to air pollutants and adverse health effects. Results of epidemiologic studies are used by U.S. EPA in developing air quality standards to protect the public from the health effects of air pollutants. A major challenge in environmental epidemiology is adequate exposure characterization. Numerous health studies have used measurements from a few central-site ambient monitors to characterize air pollution exposures. Relying solely on central-site ambient monitors does not account for the spatial-heterogeneity of ambient air pollution patterns, the temporal variability in ambient concentrations, nor the influence of infiltration and indoor sources. Central-site monitoring becomes even more problematic for certain air pollutants that exhibit significant spatial heterogeneity. Statistical interpolation techniques and passive monitoring methods can provide additional spatial resolution in ambient concentration estimates. In addition, spatio-temporal models, which integrate GIS data and other factors, such as meteorology, have also been developed to produce more resolved estimates of ambient concentrations. Models, such as the Community Multi-Scale Air Quality (CMAQ) model, estimate ambient concentrations by combining information on meteorology, source emissions, and chemical-fate and transport. Hybrid modeling approaches, which integrate regional scale models with local scale dispersion

What Fuzzy HOS May Mean

DTIC Science & Technology

1978-11-01

a fuzzy set of real numbers clustered around m, or as a possibility distribution on the value of some ill-known quantity. A fuzzy relation R on the...distribution of . va.- nossibly clustered around some mean value. STho -Ict.n uf F to X is f. Moreover, It should be noticed that the image of a *uz!y L...10) 1(•)(y)= sup Rjin (i(x),• ()(y)) xcX One may verify that 11(-())(z)= sup min (V(x),N)( 0)(×)(z)) . Gmx ) xCX •) ’ . This shows that the extension

Transonic Wind Tunnel Measurements of Tailplane and Elevator Effectiveness of the Jindivik 203B Target Aircraft,

DTIC Science & Technology

1980-09-01

0 Q 4W i Im 0 0000 Uz 00000 00000 00000 00000 0oco 0 00000 00000 00000 00000 0000 11111 I If J il l ti l l I -J 000 0000- mooc 00000 0000 i f ! ! ! ,I...Joint Intelligence Organisation 4 Defence Library 5 Document Exchange Centre, D.I.S.B. 6-23 Aeronautical Research Laboratories Chief Superintendent...24 Library 25 Superintendent - Aerodynamics Division 26 Divisional File - Aerodynamics 27 Author: B. D. Fairlie 28 Transonic Aerodynamics Group 29-33

Asteroid Lightcurve Analysis at the Oakley Southern Sky Observatory: 2011 November-December

NASA Astrophysics Data System (ADS)

Melton, Elizabeth; Carver, Spencer; Harris, Andrew; Karnemaat, Ryan; Klaasse, Matthew; Ditteon, Richard

2012-07-01

Photometric data for 26 asteroids were collected over 20 nights of observing during 2011 November through December at the Oakley Southern Sky Observatory. The asteroids were: 664 Judith, 739 Mandeville, 781 Kartvelia, 871 Amneris, 971 Alsatia, 1577 Reiss, 2068 Dangreen, 2745 San Martin, 2870 Haupt, 2909 Hoshino- ie, 3041 Webb, 4359 Berlage, 4363 Sergej, 4804 Pasteur, 5870 Baltimore, (5874) 1989 XB, 6121 Plachinda, 6172 Prokofeana, 6402 Holstein, (10765) 1990 UZ , 12738 Satoshimiki, 16358 Plesetsk, (23276) 2000 YT101, (24475) 2000 VN2, (96487) 1998 JU1, (98129) 2000 SD25.

Energy Harvesting and Storage Systems for Future AF Vehicles

DTIC Science & Technology

2012-05-11

of Bi dopant . Thermal conductivity are little influenced by Bi (Fig. B 12c ). From the result of the figure-of-merit (Fig. B12d), 3 at% Bi doped...type doping element, and K is n-type dopant while Ag doped Mg2Si has a transition from n-type top-type at 350C. ZT of these TE alloys are much lower...metal (2 llflll Eledrolyte - Uthium phosphorus oxynitride (UPON) Uz.gPOnNo.45 (2 llfll) developed by ORNL c.thode - Uthium cobalt oxide UCo02(6

Improving predictions of large scale soil carbon dynamics: Integration of fine-scale hydrological and biogeochemical processes, scaling, and benchmarking

NASA Astrophysics Data System (ADS)

Riley, W. J.; Dwivedi, D.; Ghimire, B.; Hoffman, F. M.; Pau, G. S. H.; Randerson, J. T.; Shen, C.; Tang, J.; Zhu, Q.

2015-12-01

Numerical model representations of decadal- to centennial-scale soil-carbon dynamics are a dominant cause of uncertainty in climate change predictions. Recent attempts by some Earth System Model (ESM) teams to integrate previously unrepresented soil processes (e.g., explicit microbial processes, abiotic interactions with mineral surfaces, vertical transport), poor performance of many ESM land models against large-scale and experimental manipulation observations, and complexities associated with spatial heterogeneity highlight the nascent nature of our community's ability to accurately predict future soil carbon dynamics. I will present recent work from our group to develop a modeling framework to integrate pore-, column-, watershed-, and global-scale soil process representations into an ESM (ACME), and apply the International Land Model Benchmarking (ILAMB) package for evaluation. At the column scale and across a wide range of sites, observed depth-resolved carbon stocks and their 14C derived turnover times can be explained by a model with explicit representation of two microbial populations, a simple representation of mineralogy, and vertical transport. Integrating soil and plant dynamics requires a 'process-scaling' approach, since all aspects of the multi-nutrient system cannot be explicitly resolved at ESM scales. I will show that one approach, the Equilibrium Chemistry Approximation, improves predictions of forest nitrogen and phosphorus experimental manipulations and leads to very different global soil carbon predictions. Translating model representations from the site- to ESM-scale requires a spatial scaling approach that either explicitly resolves the relevant processes, or more practically, accounts for fine-resolution dynamics at coarser scales. To that end, I will present recent watershed-scale modeling work that applies reduced order model methods to accurately scale fine-resolution soil carbon dynamics to coarse-resolution simulations. Finally, we contend that creating believable soil carbon predictions requires a robust, transparent, and community-available benchmarking framework. I will present an ILAMB evaluation of several of the above-mentioned approaches in ACME, and attempt to motivate community adoption of this evaluation approach.

The relative influence of geographic location and reach-scale habitat on benthic invertebrate assemblages in six ecoregions

USGS Publications Warehouse

Munn, M.D.; Waite, I.R.; Larsen, D.P.; Herlihy, A.T.

2009-01-01

The objective of this study was to determine the relative influence of reach-specific habitat variables and geographic location on benthic invertebrate assemblages within six ecoregions across the Western USA. This study included 417 sites from six ecoregions. A total of 301 taxa were collected with the highest richness associated with ecoregions dominated by streams with coarse substrate (19-29 taxa per site). Lowest richness (seven to eight taxa per site) was associated with ecoregions dominated by fine-grain substrate. Principle component analysis (PCA) on reach-scale habitat separated the six ecoregions into those in high-gradient mountainous areas (Coast Range, Cascades, and Southern Rockies) and those in lower-gradient ecoregions (Central Great Plains and Central California Valley). Nonmetric multidimensional scaling (NMS) models performed best in ecoregions dominated by coarse-grain substrate and high taxa richness, along with coarse-grain substrates sites combined from multiple ecoregions regardless of location. In contrast, ecoregions or site combinations dominated by fine-grain substrate had poor model performance (high stress). Four NMS models showed that geographic location (i.e. latitude and longitude) was important for: (1) all ecoregions combined, (2) all sites dominated by coarse-grain sub strate combined, (3) Cascades Ecoregion, and (4) Columbia Ecoregion. Local factors (i.e. substrate or water temperature) seem to be overriding factors controlling invertebrate composition across the West, regardless of geographic location. ?? The Author(s) 2008.

Uncertainties of Large-Scale Forcing Caused by Surface Turbulence Flux Measurements and the Impacts on Cloud Simulations at the ARM SGP Site

NASA Astrophysics Data System (ADS)

Tang, S.; Xie, S.; Tang, Q.; Zhang, Y.

2017-12-01

Two types of instruments, the eddy correlation flux measurement system (ECOR) and the energy balance Bowen ratio system (EBBR), are used at the Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site to measure surface latent and sensible fluxes. ECOR and EBBR typically sample different land surface types, and the domain-mean surface fluxes derived from ECOR and EBBR are not always consistent. The uncertainties of the surface fluxes will have impacts on the derived large-scale forcing data and further affect the simulations of single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulation models (LES), especially for the shallow-cumulus clouds which are mainly driven by surface forcing. This study aims to quantify the uncertainties of the large-scale forcing caused by surface turbulence flux measurements and investigate the impacts on cloud simulations using long-term observations from the ARM SGP site.

Modelling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices

NASA Astrophysics Data System (ADS)

Reichstein, M.; Rey, A.; Freibauer, A.; Tenhunen, J.; Valentini, R.; Soil Respiration Synthesis Team

2003-04-01

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, inter-annual and spatial variability of soil respiration as affected by water availability, temperature and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g. leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical non-linear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and inter-site variability of soil respiration with a mean absolute error of 0.82 µmol m-2 s-1. The parameterised model exhibits the following principal properties: 1) At a relative amount of upper-layer soil water of 16% of field capacity half-maximal soil respiration rates are reached. 2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. 3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly time-scale we employed the approach by Raich et al. (2002, Global Change Biol. 8, 800-812) that used monthly precipitation and air temperature to globally predict soil respiration (T&P-model). While this model was able to explain some of the month-to-month variability of soil respiration, it failed to capture the inter-site variability, regardless whether the original or a new optimized model parameterization was used. In both cases, the residuals were strongly related to maximum site leaf area index. Thus, for a monthly time scale we developed a simple T&P&LAI-model that includes leaf area index as an additional predictor of soil respiration. This extended but still simple model performed nearly as well as the more detailed time-step model and explained 50 % of the overall and 65% of the site-to-site variability. Consequently, better estimates of globally distributed soil respiration should be obtained with the new model driven by satellite estimates of leaf area index.

Project M: Scale Model of Lunar Landing Site of Apollo 17

NASA Technical Reports Server (NTRS)

O'Brien, Hollie; Crain, Timothy P.

2010-01-01

The basis of the project was creating a scale model representation of the Apollo 17 lunar landing site. Vital components included surface slope characteristics, crater sizes and locations, prominent rocks, and lighting conditions. The model was made for Project M support when evaluating approach and terminal descent as well as when planning surface operations with respect to the terrain. The project had five main mi lestones during the length of the project. The first was examining the best method to use to re-create the Apollo 17 landing site and then reviewing research fmdings with Dr. Tim Crain and EO staff which occurred on June 25, 2010 at a meeting. The second step was formulating a construction plan, budget, and schedule and then presenting the plan for authority to proceed which occurred on July 6,2010. The third part was building a prototype to test materials and building processes which were completed by July 13, 2010. Next was assembling the landing site model and presenting a mid-term construction status report on July 29, 2010. The fifth and final milestone was demonstrating the model and presenting an exit pitch which happened on August 4, 2010. The project was very technical: it needed a lot of research about moon topography, lighting conditions and angles of the sun on the moon, Apollo 17, and Autonomous Landing and Hazard Avoidance Technology (ALHAT), before starting the actual building process. This required using Spreadsheets, searching internet sources and conducting personal meetings with project representatives. This information assisted the interns in deciding the scale of the model with respect to cracks, craters and rocks and their relative sizes as the objects mentioned could interfere with any of the Lunar Landers: Apollo, Project M and future Landers. The project concluded with the completion of a three dimensional scale model of the Apollo 17 Lunar landing site. This model assists Project M members because they can now visualize approach phase, terminal descent phase, and surface phase operations on the physical model. The project had an additional requirement that was also satisfied: the granite table the model was placed on must be returnable to its original condition if needed in the future.

The role of physical habitat and sampling effort on estimates of benthic macroinvertebrate taxonomic richness at basin and site scales.

PubMed

Silva, Déborah R O; Ligeiro, Raphael; Hughes, Robert M; Callisto, Marcos

2016-06-01

Taxonomic richness is one of the most important measures of biological diversity in ecological studies, including those with stream macroinvertebrates. However, it is impractical to measure the true richness of any site directly by sampling. Our objective was to evaluate the effect of sampling effort on estimates of macroinvertebrate family and Ephemeroptera, Plecoptera, and Trichoptera (EPT) genera richness at two scales: basin and stream site. In addition, we tried to determine which environmental factors at the site scale most influenced the amount of sampling effort needed. We sampled 39 sites in the Cerrado biome (neotropical savanna). In each site, we obtained 11 equidistant samples of the benthic assemblage and multiple physical habitat measurements. The observed basin-scale richness achieved a consistent estimation from Chao 1, Jack 1, and Jack 2 richness estimators. However, at the site scale, there was a constant increase in the observed number of taxa with increased number of samples. Models that best explained the slope of site-scale sampling curves (representing the necessity of greater sampling effort) included metrics that describe habitat heterogeneity, habitat structure, anthropogenic disturbance, and water quality, for both macroinvertebrate family and EPT genera richness. Our results demonstrate the importance of considering basin- and site-scale sampling effort in ecological surveys and that taxa accumulation curves and richness estimators are good tools for assessing sampling efficiency. The physical habitat explained a significant amount of the sampling effort needed. Therefore, future studies should explore the possible implications of physical habitat characteristics when developing sampling objectives, study designs, and calculating the needed sampling effort.

The Rangeland Hydrology and Erosion Model

NASA Astrophysics Data System (ADS)

Nearing, M. A.

2016-12-01

The Rangeland Hydrology and Erosion Model (RHEM) is a process-based model that was designed to address rangelands conditions. RHEM is designed for government agencies, land managers and conservationists who need sound, science-based technology to model, assess, and predict runoff and erosion rates on rangelands and to assist in evaluating rangeland conservation practices effects. RHEM is an event-based model that estimates runoff, erosion, and sediment delivery rates and volumes at the spatial scale of the hillslope and the temporal scale of as single rainfall event. It represents erosion processes under normal and fire-impacted rangeland conditions. Moreover, it adopts a new splash erosion and thin sheet-flow transport equation developed from rangeland data, and it links the model hydrologic and erosion parameters with rangeland plant community by providing a new system of parameter estimation equations based on 204 plots at 49 rangeland sites distributed across 15 western U.S. states. A dynamic partial differential sediment continuity equation is used to model the total detachment rate of concentrated flow and rain splash and sheet flow. RHEM is also designed to be used as a calculator, or "engine", within other watershed scale models. From the research perspective RHEM acts as a vehicle for incorporating new scientific findings from rangeland infiltration, runoff, and erosion studies. Current applications of the model include: 1) a web site for general use (conservation planning, research, etc.), 2) National Resource Inventory reports to Congress, 3) as a computational engine within watershed scale models (e.g., KINEROS, HEC), 4) Ecological Site & State and Transition Descriptions, 5) proposed in 2015 to become part of the NRCS Desktop applications for field offices.

Evaluating the performance of different predictor strategies in regression-based downscaling with a focus on glacierized mountain environments

NASA Astrophysics Data System (ADS)

Hofer, Marlis; Nemec, Johanna

2016-04-01

This study presents first steps towards verifying the hypothesis that uncertainty in global and regional glacier mass simulations can be reduced considerably by reducing the uncertainty in the high-resolution atmospheric input data. To this aim, we systematically explore the potential of different predictor strategies for improving the performance of regression-based downscaling approaches. The investigated local-scale target variables are precipitation, air temperature, wind speed, relative humidity and global radiation, all at a daily time scale. Observations of these target variables are assessed from three sites in geo-environmentally and climatologically very distinct settings, all within highly complex topography and in the close proximity to mountain glaciers: (1) the Vernagtbach station in the Northern European Alps (VERNAGT), (2) the Artesonraju measuring site in the tropical South American Andes (ARTESON), and (3) the Brewster measuring site in the Southern Alps of New Zealand (BREWSTER). As the large-scale predictors, ERA interim reanalysis data are used. In the applied downscaling model training and evaluation procedures, particular emphasis is put on appropriately accounting for the pitfalls of limited and/or patchy observation records that are usually the only (if at all) available data from the glacierized mountain sites. Generalized linear models and beta regression are investigated as alternatives to ordinary least squares regression for the non-Gaussian target variables. By analyzing results for the three different sites, five predictands and for different times of the year, we look for systematic improvements in the downscaling models' skill specifically obtained by (i) using predictor data at the optimum scale rather than the minimum scale of the reanalysis data, (ii) identifying the optimum predictor allocation in the vertical, and (iii) considering multiple (variable, level and/or grid point) predictor options combined with state-of-art empirical feature selection tools. First results show that in particular for air temperature, those downscaling models based on direct predictor selection show comparative skill like those models based on multiple predictors. For all other target variables, however, multiple predictor approaches can considerably outperform those models based on single predictors. Including multiple variable types emerges as the most promising predictor option (in particular for wind speed at all sites), even if the same predictor set is used across the different cases.

Accretion in Close Pre-Main-Sequence Binaries

NASA Astrophysics Data System (ADS)

Ardila, David

2010-09-01

We propose to use COS to observe the circumbinary accretion flow in pre-main sequence binaries as a function of orbital phase. These observations will help us understand how the magnetosphere captures circumbinary gas, test model predictions regarding the importance of the mass ratio in directing the accretion flows, and study the kinematics of the gas filling the circumbinary gap. We will observe UZ Tau E {mass ratio q=0.3, e=0.33} and DQ Tau {q=1, e=0.58} in four phases, over three orbital periods, using G160M and G230L. The targets are Classical T Tauri stars for which the circumstellar disks are severely truncated. Our primary observables will be the CIV {1550 A} lines, formed at the footpoints of the accretion flow onto the star. We expect to observe the ebb and flow of the line shape, centroid, and flux as a function of orbital phase. The low-resolution NUV continuum observations will provide an independent measurement of the total accretion rate.

Understanding CO2 Plume Behavior and Basin-Scale Pressure Changes during Sequestration Projects through the use of Reservoir Fluid Modeling

USGS Publications Warehouse

Leetaru, H.E.; Frailey, S.M.; Damico, J.; Mehnert, E.; Birkholzer, J.; Zhou, Q.; Jordan, P.D.

2009-01-01

Large scale geologic sequestration tests are in the planning stages around the world. The liability and safety issues of the migration of CO2 away from the primary injection site and/or reservoir are of significant concerns for these sequestration tests. Reservoir models for simulating single or multi-phase fluid flow are used to understand the migration of CO2 in the subsurface. These models can also help evaluate concerns related to brine migration and basin-scale pressure increases that occur due to the injection of additional fluid volumes into the subsurface. The current paper presents different modeling examples addressing these issues, ranging from simple geometric models to more complex reservoir fluid models with single-site and basin-scale applications. Simple geometric models assuming a homogeneous geologic reservoir and piston-like displacement have been used for understanding pressure changes and fluid migration around each CO2 storage site. These geometric models are useful only as broad approximations because they do not account for the variation in porosity, permeability, asymmetry of the reservoir, and dip of the beds. In addition, these simple models are not capable of predicting the interference between different injection sites within the same reservoir. A more realistic model of CO2 plume behavior can be produced using reservoir fluid models. Reservoir simulation of natural gas storage reservoirs in the Illinois Basin Cambrian-age Mt. Simon Sandstone suggest that reservoir heterogeneity will be an important factor for evaluating storage capacity. The Mt. Simon Sandstone is a thick sandstone that underlies many significant coal fired power plants (emitting at least 1 million tonnes per year) in the midwestern United States including the states of Illinois, Indiana, Kentucky, Michigan, and Ohio. The initial commercial sequestration sites are expected to inject 1 to 2 million tonnes of CO2 per year. Depending on the geologic structure and permeability anisotropy, the CO2 injected into the Mt. Simon are expected to migrate less than 3 km. After 30 years of continuous injection followed by 100 years of shut-in, the plume from a 1 million tonnes a year injection rate is expected to migrate 1.6 km for a 0 degree dip reservoir and over 3 km for a 5 degree dip reservoir. The region where reservoir pressure increases in response to CO2 injection is typically much larger than the CO2 plume. It can thus be anticipated that there will be basin wide interactions between different CO2 injection sources if multiple, large volume sites are developed. This interaction will result in asymmetric plume migration that may be contrary to reservoir dip. A basin- scale simulation model is being developed to predict CO2 plume migration, brine displacement, and pressure buildup for a possible future sequestration scenario featuring multiple CO2 storage sites within the Illinois Basin Mt. Simon Sandstone. Interactions between different sites will be evaluated with respect to impacts on pressure and CO2 plume migration patterns. ?? 2009 Elsevier Ltd. All rights reserved.

Measurement and prediction of post-fire erosion at the hillslope scale, Colorado Front Range

Treesearch

Juan de Dios Benavides-Solorio; Lee H. MacDonald

2005-01-01

Post-fire soil erosion is of considerable concern because of the potential decline in site productivity and adverse effects on downstream resources. For the Colorado Front Range there is a paucity of post-fire erosion data and a corresponding lack of predictive models. This study measured hillslope-scale sediment production rates and site characteristics for three wild...

Model for teaching population health and community-based care across diverse clinical experiences.

PubMed

Van Dyk, Elizabeth J; Valentine-Maher, Sarah K; Tracy, Janet P

2015-02-01

The pillars constructivist model is designed to offer a unifying clinical paradigm to support consistent learning opportunities across diverse configurations of community and public health clinical sites. Thirty-six students and six faculty members participated in a mixed methods evaluation to assess the model after its inaugural semester of implementation. The evaluation methods included a rating scale that measures the model's ability to provide consistent learning opportunities at both population health and direct care sites, a case study to measure student growth within the five conceptual pillars, and a faculty focus group. Results revealed that the model served as an effective means of clinical education to support the use of multiple, small-scale public health sites. Although measurements of student growth within the pillars are inconclusive, the findings suggest efficacy. The authors recommend the continued use of the pillars constructivist model in baccalaureate programs, with further study of the author-designed evaluation tools. Copyright 2015, SLACK Incorporated.

A potential-energy scaling model to simulate the initial stages of thin-film growth

NASA Technical Reports Server (NTRS)

Heinbockel, J. H.; Outlaw, R. A.; Walker, G. H.

1983-01-01

A solid on solid (SOS) Monte Carlo computer simulation employing a potential energy scaling technique was used to model the initial stages of thin film growth. The model monitors variations in the vertical interaction potential that occur due to the arrival or departure of selected adatoms or impurities at all sites in the 400 sq. ft. array. Boltzmann ordered statistics are used to simulate fluctuations in vibrational energy at each site in the array, and the resulting site energy is compared with threshold levels of possible atomic events. In addition to adsorption, desorption, and surface migration, adatom incorporation and diffusion of a substrate atom to the surface are also included. The lateral interaction of nearest, second nearest, and third nearest neighbors is also considered. A series of computer experiments are conducted to illustrate the behavior of the model.

Multi-scale habitat selection in highly territorial bird species: Exploring the contribution of nest, territory and landscape levels to site choice in breeding rallids (Aves: Rallidae)

NASA Astrophysics Data System (ADS)

Jedlikowski, Jan; Chibowski, Piotr; Karasek, Tomasz; Brambilla, Mattia

2016-05-01

Habitat selection often involves choices made at different spatial scales, but the underlying mechanisms are still poorly understood, and studies that investigate the relative importance of individual scales are rare. We investigated the effect of three spatial scales (landscape, territory, nest-site) on the occurrence pattern of little crake Zapornia parva and water rail Rallus aquaticus at 74 ponds in the Masurian Lakeland, Poland. Habitat structure, food abundance and water chemical parameters were measured at nests and random points within landscape plots (from 300-m to 50-m radius), territory (14-m) and nest-site plots (3-m). Regression analyses suggested that the most relevant scale was territory level, followed by landscape, and finally by nest-site for both species. Variation partitioning confirmed this pattern for water rail, but also highlighted the importance of nest-site (the level explaining the highest share of unique variation) for little crake. The most important variables determining the occurrence of both species were water body fragmentation (landscape), vegetation density (territory) and water depth (at territory level for little crake, and at nest-site level for water rail). Finally, for both species multi-scale models including factors from different levels were more parsimonious than single-scale ones, i.e. habitat selection was likely a multi-scale process. The importance of particular spatial scales seemed more related to life-history traits than to the extent of the scales considered. In the case of our study species, the territory level was highly important likely because both rallids have to obtain all the resources they need (nest site, food and mates) in relatively small areas, the multi-purpose territories they defend.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pau, G. S. H.; Bisht, G.; Riley, W. J.

Existing land surface models (LSMs) describe physical and biological processes that occur over a wide range of spatial and temporal scales. For example, biogeochemical and hydrological processes responsible for carbon (CO 2, CH 4) exchanges with the atmosphere range from the molecular scale (pore-scale O 2 consumption) to tens of kilometers (vegetation distribution, river networks). Additionally, many processes within LSMs are nonlinearly coupled (e.g., methane production and soil moisture dynamics), and therefore simple linear upscaling techniques can result in large prediction error. In this paper we applied a reduced-order modeling (ROM) technique known as "proper orthogonal decomposition mapping method" thatmore » reconstructs temporally resolved fine-resolution solutions based on coarse-resolution solutions. We developed four different methods and applied them to four study sites in a polygonal tundra landscape near Barrow, Alaska. Coupled surface–subsurface isothermal simulations were performed for summer months (June–September) at fine (0.25 m) and coarse (8 m) horizontal resolutions. We used simulation results from three summer seasons (1998–2000) to build ROMs of the 4-D soil moisture field for the study sites individually (single-site) and aggregated (multi-site). The results indicate that the ROM produced a significant computational speedup (> 10 3) with very small relative approximation error (< 0.1%) for 2 validation years not used in training the ROM. We also demonstrate that our approach: (1) efficiently corrects for coarse-resolution model bias and (2) can be used for polygonal tundra sites not included in the training data set with relatively good accuracy (< 1.7% relative error), thereby allowing for the possibility of applying these ROMs across a much larger landscape. By coupling the ROMs constructed at different scales together hierarchically, this method has the potential to efficiently increase the resolution of land models for coupled climate simulations to spatial scales consistent with mechanistic physical process representation.« less

Scaling-Relation-Based Analysis of Bifunctional Catalysis: The Case for Homogeneous Bimetallic Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, Mie; Medford, Andrew J.; Norskov, Jens K.

Here, we present a generic analysis of the implications of energetic scaling relations on the possibilities for bifunctional gains at homogeneous bimetallic alloy catalysts. Such catalysts exhibit a large number of interface sites, where second-order reaction steps can involve intermediates adsorbed at different active sites. Using different types of model reaction schemes, we show that such site-coupling reaction steps can provide bifunctional gains that allow for a bimetallic catalyst composed of two individually poor catalyst materials to approach the activity of the optimal monomaterial catalyst. However, bifunctional gains cannot result in activities higher than the activity peak of the monomaterialmore » volcano curve as long as both sites obey similar scaling relations, as is generally the case for bimetallic catalysts. These scaling-relation-imposed limitations could be overcome by combining different classes of materials such as metals and oxides.« less

Scaling-Relation-Based Analysis of Bifunctional Catalysis: The Case for Homogeneous Bimetallic Alloys

DOE PAGES

Andersen, Mie; Medford, Andrew J.; Norskov, Jens K.; ...

2017-04-14

Here, we present a generic analysis of the implications of energetic scaling relations on the possibilities for bifunctional gains at homogeneous bimetallic alloy catalysts. Such catalysts exhibit a large number of interface sites, where second-order reaction steps can involve intermediates adsorbed at different active sites. Using different types of model reaction schemes, we show that such site-coupling reaction steps can provide bifunctional gains that allow for a bimetallic catalyst composed of two individually poor catalyst materials to approach the activity of the optimal monomaterial catalyst. However, bifunctional gains cannot result in activities higher than the activity peak of the monomaterialmore » volcano curve as long as both sites obey similar scaling relations, as is generally the case for bimetallic catalysts. These scaling-relation-imposed limitations could be overcome by combining different classes of materials such as metals and oxides.« less

The acid-base titration of montmorillonite

NASA Astrophysics Data System (ADS)

Bourg, I. C.; Sposito, G.; Bourg, A. C.

2003-12-01

Proton binding to clay minerals plays an important role in the chemical reactivity of soils (e.g., acidification, retention of nutrients or pollutants). If should also affect the performance of clay barriers for waste disposal. The surface acidity of clay minerals is commonly modelled empirically by assuming generic amphoteric surface sites (>SOH) on a flat surface, with fitted site densities and acidity constant. Current advances in experimental methods (notably spectroscopy) are rapidly improving our understanding of the structure and reactivity of the surface of clay minerals (arrangement of the particles, nature of the reactive surface sites, adsorption mechanisms). These developments are motivated by the difficulty of modelling the surface chemistry of mineral surfaces at the macro-scale (e.g., adsorption or titration) without a detailed (molecular-scale) picture of the mechanisms, and should be progressively incorporated into surface complexation models. In this view, we have combined recent estimates of montmorillonite surface properties (surface site density and structure, edge surface area, surface electrostatic potential) with surface site acidities obtained from the titration of alpha-Al2O3 and SiO2, and a novel method of accounting for the unknown initial net proton surface charge of the solid. The model predictions were compared to experimental titrations of SWy-1 montmorillonite and purified MX-80 bentonite in 0.1-0.5 mol/L NaClO4 and 0.005-0.5 mol/L NaNO3 background electrolytes, respectively. Most of the experimental data were appropriately described by the model after we adjusted a single parameter (silanol sites on the surface of montmorillonite were made to be slightly more acidic than those of silica). At low ionic strength and acidic pH the model underestimated the buffering capacity of the montmorillonite, perhaps due to clay swelling or to the interlayer adsorption of dissolved aluminum. The agreement between our model and the experimental data illustrates the complementarity of molecular and macro-scale descriptions of the clay reactivity.

Multiscale site-response mapping: A case study of Parkfield, California

USGS Publications Warehouse

Thompson, E.M.; Baise, L.G.; Kayen, R.E.; Morgan, E.C.; Kaklamanos, J.

2011-01-01

The scale of previously proposed methods for mapping site-response ranges from global coverage down to individual urban regions. Typically, spatial coverage and accuracy are inversely related.We use the densely spaced strong-motion stations in Parkfield, California, to estimate the accuracy of different site-response mapping methods and demonstrate a method for integrating multiple site-response estimates from the site to the global scale. This method is simply a weighted mean of a suite of different estimates, where the weights are the inverse of the variance of the individual estimates. Thus, the dominant site-response model varies in space as a function of the accuracy of the different models. For mapping applications, site-response models should be judged in terms of both spatial coverage and the degree of correlation with observed amplifications. Performance varies with period, but in general the Parkfield data show that: (1) where a velocity profile is available, the square-rootof- impedance (SRI) method outperforms the measured VS30 (30 m divided by the S-wave travel time to 30 m depth) and (2) where velocity profiles are unavailable, the topographic slope method outperforms surficial geology for short periods, but geology outperforms slope at longer periods. We develop new equations to estimate site response from topographic slope, derived from the Next Generation Attenuation (NGA) database.

Magmatic processes in the layered Series of the Skaergaard intrusion inferred from core and rim compositions of plagioclase

NASA Astrophysics Data System (ADS)

Brown, W. L.; Toplis, M. J.

2003-04-01

Due to slow NaSi-CaAl exchange in plagioclase, the proportion of the anorthite component (An) may be considered essentially a primary feature in magmatic bodies such as small layered intrusions. Thus, An provides a potential window into the evolution of such magmatic systems on various length scales. In order to assess the utility of this approach, 13 thin sections covering the principal zones and sub-zones of the Layered Series of the Skaergaard intrusion, East Greenland, were studied. In each thin section 90 to 150 analyses of plagioclase were made using an electron microprobe. Analyses were made in grain centres and at grain edges, particular attention being paid to plagioclase-plagioclase contacts. The cores of large and moderately sized crystals show narrow compositional ranges, 90% of analyses lying within 3 mol% of the mean. In accordance with previous studies, we find that mean core compositions vary continuously with stratigraphic height, from ˜An70 at the lowest levels, to ˜An30 at the top of Upper Zone (UZ). Rim compositions of touching plagioclase also show strong maxima in their mode, but the variation of this composition with stratigraphic height is distinctly different from that of crystal cores. In the Lower Zone (LZ) and lower Middle Zone (MZ), the most abundant rim compositions are systematically An50± 1, core and rim compositions converging in the lower MZ. In the upper MZ to UZ, rim compositions are very similar to corresponding cores, but locally may be more evolved, particularly when plagioclase is intergrown with quartz. The systematic decrease of An as a function of stratigraphic height is strong evidence in favour of fractional crystallization of the main liquid. However, the fact that plagioclase zoning does not extend to nearly pure albite in the vast majority of rocks implies mobility of intercumulus liquid. If compaction (expulsion) were the mechanism responsible for this, it would be difficult to explain the remarkably constant cut-off in rim compositions at An50 in the LZ and lower MZ. On the other hand, this cut-off corresponds to the An content at magnetite saturation, which leads us to propose that the observed features are the result of a density inversion in the liquid following oxide saturation. This density inversion causes the intercumulus liquid to become gravitationally unstable relative to the overlying main liquid leading to compositional convection in the upper LZ and MZ, a hypothesis consistent with the adcumulus texture of those rocks.

JWST Full-Scale Model on Display in Germany

NASA Image and Video Library

2010-03-10

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Munich, Germany Credit: EADS Astrium

JWST Full-Scale Model on Display in Germany

NASA Image and Video Library

2017-12-08

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Munich, Germany Credit: EADS Astrium

Harbour porpoise distribution can vary at small spatiotemporal scales in energetic habitats

NASA Astrophysics Data System (ADS)

Benjamins, Steven; van Geel, Nienke; Hastie, Gordon; Elliott, Jim; Wilson, Ben

2017-07-01

Marine habitat heterogeneity underpins species distribution and can be generated through interactions between physical and biological drivers at multiple spatiotemporal scales. Passive acoustic monitoring (PAM) is used worldwide to study potential impacts of marine industrial activities on cetaceans, but understanding of animals' site use at small spatiotemporal scales (<1 km, <1 day) remains limited. Small-scale variability in vocalising harbour porpoise (Phocoena phocoena) distribution within two Scottish marine renewable energy development (MRED) sites was investigated by deploying dense arrays of C-POD passive acoustic detectors at a wave energy test site (the European Marine Energy Centre [Billia Croo, Orkney]) and by a minor tidal-stream site (Scarba [Inner Hebrides]). Respective arrays consisted of 7 and 11 moorings containing two C-PODs each and were deployed for up to 55 days. Minimum inter-mooring distances varied between 300-600 m. All C-POD data were analysed at a temporal resolution of whole minutes, with each minute classified as 1 or 0 on the basis of presence/absence of porpoise click trains (Porpoise-Positive Minutes/PPMs). Porpoise detection rates were analysed using Generalised Additive Models (GAMs) with Generalised Estimation Equations (GEEs). Although there were many porpoise detections (wave test site: N=3,432; tidal-stream site: N=17,366), daily detection rates varied significantly within both arrays. Within the wave site array (<1 km diameter), average daily detection rates varied from 4.3 to 14.8 PPMs/day. Within the tidal-stream array (<2 km diameter), average daily detection rates varied from 10.3 to 49.7 PPMs/day. GAM-GEE model results for individual moorings within both arrays indicated linkages between porpoise presence and small-scale heterogeneity among different environmental covariates (e.g., tidal phase, time of day). Porpoise detection rates varied considerably but with coherent patterns between moorings only several hundred metres apart and within hours. These patterns presumably have ecological relevance. These results indicate that, in energetically active and heterogeneous areas, porpoises can display significant spatiotemporal variability in site use at scales of hundreds of metres and hours. Such variability will not be identified when using solitary moored PAM detectors (a common practice for site-based cetacean monitoring), but may be highly relevant for site-based impact assessments of MRED and other coastal developments. PAM arrays encompassing several detectors spread across a site therefore appear to be a more appropriate tool to study site-specific cetacean use of spatiotemporally heterogeneous habitat and assess the potential impacts of coastal and nearshore developments at small scales.

A model to predict stream water temperature across the conterminous USA

Treesearch

Catalina Segura; Peter Caldwell; Ge Sun; Steve McNulty; Yang Zhang

2014-01-01

Stream water temperature (ts) is a critical water quality parameter for aquatic ecosystems. However, ts records are sparse or nonexistent in many river systems. In this work, we present an empirical model to predict ts at the site scale across the USA. The model, derived using data from 171 reference sites selected from the Geospatial Attributes of Gages for Evaluating...

Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rai, Raj K.; Berg, Larry K.; Pekour, Mikhail

The assumption of sub-grid scale (SGS) horizontal homogeneity within a model grid cell, which forms the basis of SGS turbulence closures used by mesoscale models, becomes increasingly tenuous as grid spacing is reduced to a few kilometers or less, such as in many emerging high-resolution applications. Herein, we use the turbulence kinetic energy (TKE) budget equation to study the spatio-temporal variability in two types of terrain—complex (Columbia Basin Wind Energy Study [CBWES] site, north-eastern Oregon) and flat (ScaledWind Farm Technologies [SWiFT] site, west Texas) using the Weather Research and Forecasting (WRF) model. In each case six-nested domains (three domains eachmore » for mesoscale and large-eddy simulation [LES]) are used to downscale the horizontal grid spacing from 10 km to 10 m using the WRF model framework. The model output was used to calculate the values of the TKE budget terms in vertical and horizontal planes as well as the averages of grid cells contained in the four quadrants (a quarter area) of the LES domain. The budget terms calculated along the planes and the mean profile of budget terms show larger spatial variability at CBWES site than at the SWiFT site. The contribution of the horizontal derivative of the shear production term to the total production shear was found to be 45% and 15% of the total shear, at the CBWES and SWiFT sites, respectively, indicating that the horizontal derivatives applied in the budget equation should not be ignored in mesoscale model parameterizations, especially for cases with complex terrain with <10 km scale.« less

Three-dimensional geological modelling of anthropogenic deposits at small urban sites: a case study from Sheepcote Valley, Brighton, UK.

PubMed

Tame, C; Cundy, A B; Royse, K R; Smith, M; Moles, N R

2013-11-15

Improvements in computing speed and capacity and the increasing collection and digitisation of geological data now allow geoscientists to produce meaningful 3D spatial models of the shallow subsurface in many large urban areas, to predict ground conditions and reduce risk and uncertainty in urban planning. It is not yet clear how useful this 3D modelling approach is at smaller urban scales, where poorly characterised anthropogenic deposits (artificial/made ground and fill) form the dominant subsurface material and where the availability of borehole and other geological data is less comprehensive. This is important as it is these smaller urban sites, with complex site history, which frequently form the focus of urban regeneration and redevelopment schemes. This paper examines the extent to which the 3D modelling approach previously utilised at large urban scales can be extended to smaller less well-characterised urban sites, using a historic landfill site in Sheepcote Valley, Brighton, UK as a case study. Two 3D models were generated and compared using GSI3D™ software, one using borehole data only, one combining borehole data with local geological maps and results from a desk study (involving collation of available site data, including ground contour plans). These models clearly delimit the overall subsurface geology at the site, and allow visualisation and modelling of the anthropogenic deposits present. Shallow geophysical data collected from the site partially validate the 3D modelled data, and can improve GSI3D™ outputs where boundaries of anthropogenic deposits may not be clearly defined by surface, contour or borehole data. Attribution of geotechnical and geochemical properties to the 3D model is problematic without intrusive investigations and sampling. However, combining available borehole data, shallow geophysical methods and site histories may allow attribution of generic fill properties, and consequent reduction of urban development risk and uncertainty. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Predicting Model of E-commerce Site Based on the Ideas of Curve Fitting

NASA Astrophysics Data System (ADS)

Tao, Zhang; Li, Zhang; Dingjun, Chen

On the basis of the idea of the second multiplication curve fitting, the number and scale of Chinese E-commerce site is analyzed. A preventing increase model is introduced in this paper, and the model parameters are solved by the software of Matlab. The validity of the preventing increase model is confirmed though the numerical experiment. The experimental results show that the precision of preventing increase model is ideal.

Watershed modeling at the Savannah River Site.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vache, Kellie

2015-04-29

The overall goal of the work was the development of a watershed scale model of hydrological function for application to the US Department of Energy’s (DOE) Savannah River Site (SRS). The primary outcomes is a grid based hydrological modeling system that captures near surface runoff as well as groundwater recharge and contributions of groundwater to streams. The model includes a physically-based algorithm to capture both evaporation and transpiration from forestland.

Latvian Waste Management Modelling in View of Environmental Impact Reduction / Latvijas Atkritumu SAIMNIECĪBAS ATTĪSTĪBA un TĀS RADĪTĀS Ietekmes UZ Vidi SAMAZINĀŠANAS MODELĒŠANA

NASA Astrophysics Data System (ADS)

Teibe, I.; Bendere, R.; Arina, D.

2013-12-01

In the work, the life-cycle assessment approach is applied to the planning of waste management development in a seaside region (Piejūra) using the Waste Management Planning System (WAMPS) program. In Latvia, the measures to be taken for the climate change mitigation are of utmost importance - especially as related to the WM performance, since a disposal of biodegradable waste presents the primary source of GHG emissions. To reduce the amount of such waste is therefore one of the most significant goals in the State WM plan for 2013-2020, whose adoption is the greatest challenge for municipalities. The authors analyse seven models which involve widely employed biomass processing methods, are based on experimental data and intended for minimising the direct disposal of organic mass at the solid waste landfills. The numerical results obtained evidence that the thermal or biotechnological treatment of organic waste substantially reduces the negative environmental impact of WM practices - by up to 6% as compared with the currently existing. Klimata pārmaiņu samazināšanas pasākumi Latvijā atkritumu saimniecības sektorā ir īpaši svarīgi. jo bioloģiski sadalāmo atkritumu apglabāšana ir viens no būtiskākajiem SEG emisiju avotiem valstī. Pētījumā modelēti virkne sadzīves atkritumu apsaimniekošanas modeļi. kas ietver plašāk izmantotās biomasas pārstrādes metodes un samazina tiešu organiskās masas apglabāšanu cieto sadzīves atkritumu poligonos. Atkritumu apsaimniekošanas modeļu radītās vides ietekmes novērtēšanai izmantota WAMPS (Waste Management Planning System) programma, kas balstīta uz atkritumu apsaimniekošanas procesu dzīves cikla novērtējumu vienā no desmit Latvijas atkritumu apsaimniekošanas reģioniem - Piejūra. Iegūtie kvantitatīvie rezultāti norāda. ka organiskās atkritumu masas pārstrāde un stabilizēšana, izmantojot biotehnoloģijas vai termisko pārstrādi, būtiski samazina atkritumu apsaimniekošanas radīto negatīvo vides ietekmi. līdz pat 6% attiecībā pret esošās atkritumu saimniecības vides ietekmi.

Is site-specific APEX calibration necessary for field scale BMP assessment?

USDA-ARS?s Scientific Manuscript database

The possibility of extending parameter sets obtained at one site to sites with similar characteristics is appealing. This study was undertaken to test model performance and compare the effectiveness of best management practices (BMPs) using three parameters sets obtained from three watersheds when a...

GPCC - A weather generator-based statistical downscaling tool for site-specific assessment of climate change impacts

USDA-ARS?s Scientific Manuscript database

Resolution of climate model outputs are too coarse to be used as direct inputs to impact models for assessing climate change impacts on agricultural production, water resources, and eco-system services at local or site-specific scales. Statistical downscaling approaches are usually used to bridge th...

Geological modeling of submeter scale heterogeneity and its influence on tracer transport in a fluvial aquifer

NASA Astrophysics Data System (ADS)

Ronayne, Michael J.; Gorelick, Steven M.; Zheng, Chunmiao

2010-10-01

We developed a new model of aquifer heterogeneity to analyze data from a single-well injection-withdrawal tracer test conducted at the Macrodispersion Experiment (MADE) site on the Columbus Air Force Base in Mississippi (USA). The physical heterogeneity model is a hybrid that combines 3-D lithofacies to represent submeter scale, highly connected channels within a background matrix based on a correlated multivariate Gaussian hydraulic conductivity field. The modeled aquifer architecture is informed by a variety of field data, including geologic core sampling. Geostatistical properties of this hybrid heterogeneity model are consistent with the statistics of the hydraulic conductivity data set based on extensive borehole flowmeter testing at the MADE site. The representation of detailed, small-scale geologic heterogeneity allows for explicit simulation of local preferential flow and slow advection, processes that explain the complex tracer response from the injection-withdrawal test. Based on the new heterogeneity model, advective-dispersive transport reproduces key characteristics of the observed tracer recovery curve, including a delayed concentration peak and a low-concentration tail. Importantly, our results suggest that intrafacies heterogeneity is responsible for local-scale mass transfer.

Understanding Hydraulic Fracturing: A Multi-Scale Problem

DOE PAGES

Hyman, Jeffrey De'Haven; Gimenez Martinez, Joaquin; Viswanathan, Hari S.; ...

2016-09-05

Despite the impact that hydraulic fracturing has had on the energy sector, the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nano-meters to kilo-meters. We characterize flow and transport in shale formations across and between these scales using integrated computational, theoretical, and experimental efforts. At the field scale, we use discrete fracture network modeling to simulate production at a well site whose fracture network is based on a site characterization of a shale formation. At the core scale, we use triaxial fracture experiments and a finite-element discrete-elementmore » fracture propagation model with a coupled fluid solver to study dynamic crack propagation in low permeability shale. We use lattice Boltzmann pore-scale simulations and microfluidic experiments in both synthetic and real micromodels to study pore-scale flow phenomenon such as multiphase flow and mixing. A mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs.« less

Compendium of GAO’s Views on the Cost Saving Proposals of the Grace Commission. Volume 2. Individual Issue Analyses

DTIC Science & Technology

1985-02-19

CONITACT John R. Cherbini 275-9487 347 USAF 8: CONSOLIDATION AND COORDINATION OF AIR FORCE RESERVE AND AIR NATIONAL GUARD ACTIVITIES I. PPSSCC ISSUE... nowO O rAC-N’ In r-i.-l 41 E-l Z- - - U) E-4 z E- rz: E- 2 -4o w . U: >4 w~Q~ En~ o w o wE1W nH ( 14 0 uz m- H-Z U)PPz >4 W~0 E- E- W u w z U w 4ZE4E u

Evaluation of RST (Rapidly Solidified Technology) Structural Durability and Life Cycle Costs

DTIC Science & Technology

1987-10-01

n . ADAYS, Thief Prolect Engineer Structural Integrity...34 -- ,..’ 0 L:LUU, z D Cd z C ~ r 0 < 0 C/3 N < x 000 09 U LU, z 0 U, 1- U. 0 I- cc z n n 0 c 0L I-- I- w I z N cc NL C 00 Uz M Z 01 prepared from 7091...Scheme 22 LUJ I- 1.- n I- gmJ - n LUj 0 ujN mi 4 4. 23 In two specimens, residual stress depth profiles were obtained. These measurements were

Development of a microscale land use regression model for predicting NO2 concentrations at a heavy trafficked suburban area in Auckland, NZ.

PubMed

Weissert, L F; Salmond, J A; Miskell, G; Alavi-Shoshtari, M; Williams, D E

2018-04-01

Land use regression (LUR) analysis has become a key method to explain air pollutant concentrations at unmeasured sites at city or country scales, but little is known about the applicability of LUR at microscales. We present a microscale LUR model developed for a heavy trafficked section of road in Auckland, New Zealand. We also test the within-city transferability of LUR models developed at different spatial scales (local scale and city scale). Nitrogen dioxide (NO 2 ) was measured during summer at 40 sites and a LUR model was developed based on standard criteria. The results showed that LUR models are able to capture the microscale variability with the model explaining 66% of the variability in NO 2 concentrations. Predictor variables identified at this scale were street width, distance to major road, presence of awnings and number of bus stops, with the latter three also being important determinants at the local scale. This highlights the importance of street and building configurations for individual exposure at the street level. However, within-city transferability was limited with the number of bus stops being the only significant predictor variable at all spatial scales and locations tested, indicating the strong influence of diesel emissions related to bus traffic. These findings show that air quality monitoring is necessary at a high spatial density within cities in capturing small-scale variability in NO 2 concentrations at the street level and assessing individual exposure to traffic related air pollutants. Copyright © 2017. Published by Elsevier B.V.

Shoreline changes and its impact on archaeological sites in West Greenland

NASA Astrophysics Data System (ADS)

Fenger-Nielsen, R.; Kroon, A.; Elberling, B.; Hollesen, J.

2017-12-01

Coastal erosion is regarded as a major threat to archaeological sites in the Arctic region. The problem arises because the predominantly marine-focused lifeways of Arctic people means that the majority of archaeological sites are found near the coast. On a Pan-Arctic scale, coastal erosion is often explained by long-term processes such as sea level rise, lengthening of open water periods due to a decline in sea ice, and a predicted increase in the frequency of major storms. However, on a local scale other short-term processes may be important parameters determining the coastal development. In this study, we focus on the Nuuk fjord system in West Greenland, which has been inhabited over the past 4000 years by different cultures and holds around 260 registered archaeological settlements. The fjord is characterized by its large branching of narrow deep-water and well-shaded water bodies, where tidal processes and local sources of sediment supply by rivers are observed to be the dominant factors determining the coastal development. We present a regional model showing the vulnerability of the shoreline and archeological sites due to coastal processes. The model is based on a) levelling surveys and historical aerial photographs of nine specific sites distributed in the region, b) water level measurements at three sites representing the inner-, middle- and outer fjord system, c) aerial photographs, satellite images and meteorological data of the entire region used to up-scale our local information at a specific settlement scale towards a regional scale. This deals with spatial and temporal variability in erosion and accumulation patterns along the shores in fjords and open seas.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenberg, Jim; Penuelas, J.; Guenther, Alex B.

To survey landscape-scale fluxes of biogenic gases, a100-meterTeflon tube was attached to a tethered balloon as a sampling inlet for a fast response Proton Transfer Reaction Mass Spectrometer (PTRMS). Along with meteorological instruments deployed on the tethered balloon and at 3-mand outputs from a regional weather model, these observations were used to estimate landscape scale biogenic volatile organic compound fluxes with two micrometeorological techniques: mixed layer variance and surface layer gradients. This highly mobile sampling system was deployed at four field sites near Barcelona to estimate landscape-scale BVOC emission factors in a relatively short period (3 weeks). The two micrometeorologicalmore » techniques agreed within the uncertainty of the flux measurements at all four sites even though the locations had considerable heterogeneity in species distribution and complex terrain. The observed fluxes were significantly different than emissions predicted with an emission model using site-specific emission factors and land-cover characteristics. Considering the wide range in reported BVOC emission factors of VOCs for individual vegetation species (more than an order of magnitude), this flux estimation technique is useful for constraining BVOC emission factors used as model inputs.« less

Geological Investigation Program for the Site of a New Nuclear Power Plant in Hungary

NASA Astrophysics Data System (ADS)

Gerstenkorn, András; Trosits, Dalma; Chikán, Géza; János Katona, Tamás

2015-04-01

Comprehensive site evalaution program is implemented for the new Nuclear Power Plant to be constructed at Paks site in Hungary with the aim of confirmation of acceptability of the site and definition of site-related design basis data. Most extensive part of this program is to investigate geological-tectonical features of the site with particular aim on the assessment of the capability of faults at and around the site, characterization of site seismic hazard, and definition of the design basis earthquake. A brief description of the scope and methodology of the geological, seismological, geophysical, geotechnical and hydrogeological investigations will be given on the poster. Main focus of the presentation is to show the graded structure and extent of the geological investigations that follow the needs and scale of the geological modeling, starting with the site and its vicinity, as well as on the near regional and the regional scale. Geological inverstigations includes several boreholes up-to the base-rock, plenty of boreholes discovering the Pannonian and large number of shallow boreholes for investigation of more recent development. The planning of the geological investigations is based on the 3D seismic survey performed around the site, that is complemented by shallow-seimic survey at and in the vicinity of the site. The 3D geophysical imaging provides essential geodynamic information to assess the capability of near site faults and for the seismic hazard analysis, as well as for the hydrogeological modeling. The planned seismic survey gives a unique dataset for understanding the spatial relationship between individual fault segments. Planning of the research (trenching, etc.) for paleoseismic manifestations is also based on the 3D seismic survey. The seismic survey and other geophysical data (including data of space geodesy) allow the amendment of the understanding and the model of the tectonic evolution of the area and geological events. As it is known from earlier studies, seismic sources in the near regional area are the dominating contributors to the site seimic hazard. Therefore a 3D geological model will be developed for the 50 km region around the site in order to consider different geological scenarios. Site-scale investigations are aimed on the characterization of local geotechnical and hydrogeological conditions. The geotechnical investigations provide data for the evaluation of site response, i.e. the free-field ground motion response spectra, assessment of the liquefaction hazard and foundation design. Important element of the hydrogeological survey is numerical groundwater modeling. The aim of hydrogeological modeling is the summary of hydrogeological data in a numeric system, the description, simulation of underground water flow and transport conditions.

Modeling of thin film GaAs growth

NASA Technical Reports Server (NTRS)

Heinbockel, J. H.

1982-01-01

A potential scaling Monte Carlo model of crystal growth is developed. The model is a modification of the solid-on-solid method for studying crystal growth in that potentials at surface sites are continuously updated on a time scale reflecting the surface events of migration, incorporation and evaporation. The model allows for B on A type of crystal growth and lattice disregistry by the assignment of potential values at various surface sites. The surface adatoms are periodically assigned a random energy from a Boltzmann distribution and this energy determines whether the adatoms evaporate, migrate or remain stationary during the sampling interval. For each addition or migration of an adatom, the surface potentials are adjusted to reflect the adsorption, migration or desorption potential changes.

A Unified Multi-scale Model for Cross-Scale Evaluation and Integration of Hydrological and Biogeochemical Processes

NASA Astrophysics Data System (ADS)

Liu, C.; Yang, X.; Bailey, V. L.; Bond-Lamberty, B. P.; Hinkle, C.

2013-12-01

Mathematical representations of hydrological and biogeochemical processes in soil, plant, aquatic, and atmospheric systems vary with scale. Process-rich models are typically used to describe hydrological and biogeochemical processes at the pore and small scales, while empirical, correlation approaches are often used at the watershed and regional scales. A major challenge for multi-scale modeling is that water flow, biogeochemical processes, and reactive transport are described using different physical laws and/or expressions at the different scales. For example, the flow is governed by the Navier-Stokes equations at the pore-scale in soils, by the Darcy law in soil columns and aquifer, and by the Navier-Stokes equations again in open water bodies (ponds, lake, river) and atmosphere surface layer. This research explores whether the physical laws at the different scales and in different physical domains can be unified to form a unified multi-scale model (UMSM) to systematically investigate the cross-scale, cross-domain behavior of fundamental processes at different scales. This presentation will discuss our research on the concept, mathematical equations, and numerical execution of the UMSM. Three-dimensional, multi-scale hydrological processes at the Disney Wilderness Preservation (DWP) site, Florida will be used as an example for demonstrating the application of the UMSM. In this research, the UMSM was used to simulate hydrological processes in rooting zones at the pore and small scales including water migration in soils under saturated and unsaturated conditions, root-induced hydrological redistribution, and role of rooting zone biogeochemical properties (e.g., root exudates and microbial mucilage) on water storage and wetting/draining. The small scale simulation results were used to estimate effective water retention properties in soil columns that were superimposed on the bulk soil water retention properties at the DWP site. The UMSM parameterized from smaller scale simulations were then used to simulate coupled flow and moisture migration in soils in saturated and unsaturated zones, surface and groundwater exchange, and surface water flow in streams and lakes at the DWP site under dynamic precipitation conditions. Laboratory measurements of soil hydrological and biogeochemical properties are used to parameterize the UMSM at the small scales, and field measurements are used to evaluate the UMSM.

JWST Full-Scale Model on Display at GSFC

NASA Image and Video Library

2010-02-26

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Greenbelt, MD at the NASA Goddard Space Flight Center. Credit: NASA/Goddard Space Flight Center/Pat Izzo

Constructing Optimal Coarse-Grained Sites of Huge Biomolecules by Fluctuation Maximization.

PubMed

Li, Min; Zhang, John Zenghui; Xia, Fei

2016-04-12

Coarse-grained (CG) models are valuable tools for the study of functions of large biomolecules on large length and time scales. The definition of CG representations for huge biomolecules is always a formidable challenge. In this work, we propose a new method called fluctuation maximization coarse-graining (FM-CG) to construct the CG sites of biomolecules. The defined residual in FM-CG converges to a maximal value as the number of CG sites increases, allowing an optimal CG model to be rigorously defined on the basis of the maximum. More importantly, we developed a robust algorithm called stepwise local iterative optimization (SLIO) to accelerate the process of coarse-graining large biomolecules. By means of the efficient SLIO algorithm, the computational cost of coarse-graining large biomolecules is reduced to within the time scale of seconds, which is far lower than that of conventional simulated annealing. The coarse-graining of two huge systems, chaperonin GroEL and lengsin, indicates that our new methods can coarse-grain huge biomolecular systems with up to 10,000 residues within the time scale of minutes. The further parametrization of CG sites derived from FM-CG allows us to construct the corresponding CG models for studies of the functions of huge biomolecular systems.

Financial Management of a Large Multi-site Randomized Clinical Trial

PubMed Central

Sheffet, Alice J.; Flaxman, Linda; Tom, MeeLee; Hughes, Susan E.; Longbottom, Mary E.; Howard, Virginia J.; Marler, John R.; Brott, Thomas G.

2014-01-01

Background The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) received five years’ funding ($21,112,866) from the National Institutes of Health to compare carotid stenting to surgery for stroke prevention in 2,500 randomized participants at 40 sites. Aims Herein we evaluate the change in the CREST budget from a fixed to variable-cost model and recommend strategies for the financial management of large-scale clinical trials. Methods Projections of the original grant’s fixed-cost model were compared to the actual costs of the revised variable-cost model. The original grant’s fixed-cost budget included salaries, fringe benefits, and other direct and indirect costs. For the variable-cost model, the costs were actual payments to the clinical sites and core centers based upon actual trial enrollment. We compared annual direct and indirect costs and per-patient cost for both the fixed and variable models. Differences between clinical site and core center expenditures were also calculated. Results Using a variable-cost budget for clinical sites, funding was extended by no-cost extension from five to eight years. Randomizing sites tripled from 34 to 109. Of the 2,500 targeted sample size, 138 (5.5%) were randomized during the first five years and 1,387 (55.5%) during the no-cost extension. The actual per-patient costs of the variable model were 9% ($13,845) of the projected per-patient costs ($152,992) of the fixed model. Conclusions Performance-based budgets conserve funding, promote compliance, and allow for additional sites at modest additional cost. Costs of large-scale clinical trials can thus be reduced through effective management without compromising scientific integrity. PMID:24661748

Modeling sugar cane yield with a process-based model from site to continental scale: uncertainties arising from model structure and parameter values

NASA Astrophysics Data System (ADS)

Valade, A.; Ciais, P.; Vuichard, N.; Viovy, N.; Huth, N.; Marin, F.; Martiné, J.-F.

2014-01-01

Agro-Land Surface Models (agro-LSM) have been developed from the integration of specific crop processes into large-scale generic land surface models that allow calculating the spatial distribution and variability of energy, water and carbon fluxes within the soil-vegetation-atmosphere continuum. When developing agro-LSM models, a particular attention must be given to the effects of crop phenology and management on the turbulent fluxes exchanged with the atmosphere, and the underlying water and carbon pools. A part of the uncertainty of Agro-LSM models is related to their usually large number of parameters. In this study, we quantify the parameter-values uncertainty in the simulation of sugar cane biomass production with the agro-LSM ORCHIDEE-STICS, using a multi-regional approach with data from sites in Australia, La Réunion and Brazil. In ORCHIDEE-STICS, two models are chained: STICS, an agronomy model that calculates phenology and management, and ORCHIDEE, a land surface model that calculates biomass and other ecosystem variables forced by STICS' phenology. First, the parameters that dominate the uncertainty of simulated biomass at harvest date are determined through a screening of 67 different parameters of both STICS and ORCHIDEE on a multi-site basis. Secondly, the uncertainty of harvested biomass attributable to those most sensitive parameters is quantified and specifically attributed to either STICS (phenology, management) or to ORCHIDEE (other ecosystem variables including biomass) through distinct Monte-Carlo runs. The uncertainty on parameter values is constrained using observations by calibrating the model independently at seven sites. In a third step, a sensitivity analysis is carried out by varying the most sensitive parameters to investigate their effects at continental scale. A Monte-Carlo sampling method associated with the calculation of Partial Ranked Correlation Coefficients is used to quantify the sensitivity of harvested biomass to input parameters on a continental scale across the large regions of intensive sugar cane cultivation in Australia and Brazil. Ten parameters driving most of the uncertainty in the ORCHIDEE-STICS modeled biomass at the 7 sites are identified by the screening procedure. We found that the 10 most sensitive parameters control phenology (maximum rate of increase of LAI) and root uptake of water and nitrogen (root profile and root growth rate, nitrogen stress threshold) in STICS, and photosynthesis (optimal temperature of photosynthesis, optimal carboxylation rate), radiation interception (extinction coefficient), and transpiration and respiration (stomatal conductance, growth and maintenance respiration coefficients) in ORCHIDEE. We find that the optimal carboxylation rate and photosynthesis temperature parameters contribute most to the uncertainty in harvested biomass simulations at site scale. The spatial variation of the ranked correlation between input parameters and modeled biomass at harvest is well explained by rain and temperature drivers, suggesting climate-mediated different sensitivities of modeled sugar cane yield to the model parameters, for Australia and Brazil. This study reveals the spatial and temporal patterns of uncertainty variability for a highly parameterized agro-LSM and calls for more systematic uncertainty analyses of such models.

Modeling sugarcane yield with a process-based model from site to continental scale: uncertainties arising from model structure and parameter values

NASA Astrophysics Data System (ADS)

Valade, A.; Ciais, P.; Vuichard, N.; Viovy, N.; Caubel, A.; Huth, N.; Marin, F.; Martiné, J.-F.

2014-06-01

Agro-land surface models (agro-LSM) have been developed from the integration of specific crop processes into large-scale generic land surface models that allow calculating the spatial distribution and variability of energy, water and carbon fluxes within the soil-vegetation-atmosphere continuum. When developing agro-LSM models, particular attention must be given to the effects of crop phenology and management on the turbulent fluxes exchanged with the atmosphere, and the underlying water and carbon pools. A part of the uncertainty of agro-LSM models is related to their usually large number of parameters. In this study, we quantify the parameter-values uncertainty in the simulation of sugarcane biomass production with the agro-LSM ORCHIDEE-STICS, using a multi-regional approach with data from sites in Australia, La Réunion and Brazil. In ORCHIDEE-STICS, two models are chained: STICS, an agronomy model that calculates phenology and management, and ORCHIDEE, a land surface model that calculates biomass and other ecosystem variables forced by STICS phenology. First, the parameters that dominate the uncertainty of simulated biomass at harvest date are determined through a screening of 67 different parameters of both STICS and ORCHIDEE on a multi-site basis. Secondly, the uncertainty of harvested biomass attributable to those most sensitive parameters is quantified and specifically attributed to either STICS (phenology, management) or to ORCHIDEE (other ecosystem variables including biomass) through distinct Monte Carlo runs. The uncertainty on parameter values is constrained using observations by calibrating the model independently at seven sites. In a third step, a sensitivity analysis is carried out by varying the most sensitive parameters to investigate their effects at continental scale. A Monte Carlo sampling method associated with the calculation of partial ranked correlation coefficients is used to quantify the sensitivity of harvested biomass to input parameters on a continental scale across the large regions of intensive sugarcane cultivation in Australia and Brazil. The ten parameters driving most of the uncertainty in the ORCHIDEE-STICS modeled biomass at the 7 sites are identified by the screening procedure. We found that the 10 most sensitive parameters control phenology (maximum rate of increase of LAI) and root uptake of water and nitrogen (root profile and root growth rate, nitrogen stress threshold) in STICS, and photosynthesis (optimal temperature of photosynthesis, optimal carboxylation rate), radiation interception (extinction coefficient), and transpiration and respiration (stomatal conductance, growth and maintenance respiration coefficients) in ORCHIDEE. We find that the optimal carboxylation rate and photosynthesis temperature parameters contribute most to the uncertainty in harvested biomass simulations at site scale. The spatial variation of the ranked correlation between input parameters and modeled biomass at harvest is well explained by rain and temperature drivers, suggesting different climate-mediated sensitivities of modeled sugarcane yield to the model parameters, for Australia and Brazil. This study reveals the spatial and temporal patterns of uncertainty variability for a highly parameterized agro-LSM and calls for more systematic uncertainty analyses of such models.

Evaluating the potential for site-specific modification of LiDAR DEM derivatives to improve environmental planning-scale wetland identification using Random Forest classification

NASA Astrophysics Data System (ADS)

O'Neil, Gina L.; Goodall, Jonathan L.; Watson, Layne T.

2018-04-01

Wetlands are important ecosystems that provide many ecological benefits, and their quality and presence are protected by federal regulations. These regulations require wetland delineations, which can be costly and time-consuming to perform. Computer models can assist in this process, but lack the accuracy necessary for environmental planning-scale wetland identification. In this study, the potential for improvement of wetland identification models through modification of digital elevation model (DEM) derivatives, derived from high-resolution and increasingly available light detection and ranging (LiDAR) data, at a scale necessary for small-scale wetland delineations is evaluated. A novel approach of flow convergence modelling is presented where Topographic Wetness Index (TWI), curvature, and Cartographic Depth-to-Water index (DTW), are modified to better distinguish wetland from upland areas, combined with ancillary soil data, and used in a Random Forest classification. This approach is applied to four study sites in Virginia, implemented as an ArcGIS model. The model resulted in significant improvement in average wetland accuracy compared to the commonly used National Wetland Inventory (84.9% vs. 32.1%), at the expense of a moderately lower average non-wetland accuracy (85.6% vs. 98.0%) and average overall accuracy (85.6% vs. 92.0%). From this, we concluded that modifying TWI, curvature, and DTW provides more robust wetland and non-wetland signatures to the models by improving accuracy rates compared to classifications using the original indices. The resulting ArcGIS model is a general tool able to modify these local LiDAR DEM derivatives based on site characteristics to identify wetlands at a high resolution.

Allometric Scaling and Resource Limitations Model of Total Aboveground Biomass in Forest Stands: Site-scale Test of Model

NASA Astrophysics Data System (ADS)

CHOI, S.; Shi, Y.; Ni, X.; Simard, M.; Myneni, R. B.

2013-12-01

Sparseness in in-situ observations has precluded the spatially explicit and accurate mapping of forest biomass. The need for large-scale maps has raised various approaches implementing conjugations between forest biomass and geospatial predictors such as climate, forest type, soil property, and topography. Despite the improved modeling techniques (e.g., machine learning and spatial statistics), a common limitation is that biophysical mechanisms governing tree growth are neglected in these black-box type models. The absence of a priori knowledge may lead to false interpretation of modeled results or unexplainable shifts in outputs due to the inconsistent training samples or study sites. Here, we present a gray-box approach combining known biophysical processes and geospatial predictors through parametric optimizations (inversion of reference measures). Total aboveground biomass in forest stands is estimated by incorporating the Forest Inventory and Analysis (FIA) and Parameter-elevation Regressions on Independent Slopes Model (PRISM). Two main premises of this research are: (a) The Allometric Scaling and Resource Limitations (ASRL) theory can provide a relationship between tree geometry and local resource availability constrained by environmental conditions; and (b) The zeroth order theory (size-frequency distribution) can expand individual tree allometry into total aboveground biomass at the forest stand level. In addition to the FIA estimates, two reference maps from the National Biomass and Carbon Dataset (NBCD) and U.S. Forest Service (USFS) were produced to evaluate the model. This research focuses on a site-scale test of the biomass model to explore the robustness of predictors, and to potentially improve models using additional geospatial predictors such as climatic variables, vegetation indices, soil properties, and lidar-/radar-derived altimetry products (or existing forest canopy height maps). As results, the optimized ASRL estimates satisfactorily resemble the FIA aboveground biomass in terms of data distribution, overall agreement, and spatial similarity across scales. Uncertainties are quantified (ranged from 0.2 to 0.4) by taking into account the spatial mismatch (FIA plot vs. PRISM grid), heterogeneity (species composition), and an example bias scenario (= 0.2) in the root system extents.

Elimination of the Reaction Rate "Scale Effect": Application of the Lagrangian Reactive Particle-Tracking Method to Simulate Mixing-Limited, Field-Scale Biodegradation at the Schoolcraft (MI, USA) Site

NASA Astrophysics Data System (ADS)

Ding, Dong; Benson, David A.; Fernández-Garcia, Daniel; Henri, Christopher V.; Hyndman, David W.; Phanikumar, Mantha S.; Bolster, Diogo

2017-12-01

Measured (or empirically fitted) reaction rates at groundwater remediation sites are typically much lower than those found in the same material at the batch or laboratory scale. The reduced rates are commonly attributed to poorer mixing at the larger scales. A variety of methods have been proposed to account for this scaling effect in reactive transport. In this study, we use the Lagrangian particle-tracking and reaction (PTR) method to simulate a field bioremediation experiment at the Schoolcraft, MI site. A denitrifying bacterium, Pseudomonas Stutzeri strain KC (KC), was injected to the aquifer, along with sufficient substrate, to degrade the contaminant, carbon tetrachloride (CT), under anaerobic conditions. The PTR method simulates chemical reactions through probabilistic rules of particle collisions, interactions, and transformations to address the scale effect (lower apparent reaction rates for each level of upscaling, from batch to column to field scale). In contrast to a prior Eulerian reaction model, the PTR method is able to match the field-scale experiment using the rate coefficients obtained from batch experiments.

Comprehensive modeling of microRNA targets predicts functional non-conserved and non-canonical sites.

PubMed

Betel, Doron; Koppal, Anjali; Agius, Phaedra; Sander, Chris; Leslie, Christina

2010-01-01

mirSVR is a new machine learning method for ranking microRNA target sites by a down-regulation score. The algorithm trains a regression model on sequence and contextual features extracted from miRanda-predicted target sites. In a large-scale evaluation, miRanda-mirSVR is competitive with other target prediction methods in identifying target genes and predicting the extent of their downregulation at the mRNA or protein levels. Importantly, the method identifies a significant number of experimentally determined non-canonical and non-conserved sites.

The hydrological cycle at European Fluxnet sites: modeling seasonal water and energy budgets at local scale.

NASA Astrophysics Data System (ADS)

Stockli, R.; Vidale, P. L.

2003-04-01

The importance of correctly including land surface processes in climate models has been increasingly recognized in the past years. Even on seasonal to interannual time scales land surface - atmosphere feedbacks can play a substantial role in determining the state of the near-surface climate. The availability of soil moisture for both runoff and evapotranspiration is dependent on biophysical processes occuring in plants and in the soil acting on a wide time-scale from minutes to years. Fluxnet site measurements in various climatic zones are used to drive three generations of LSM's (land surface models) in order to assess the level of complexity needed to represent vegetation processes at the local scale. The three models were the Bucket model (Manabe 1969), BATS 1E (Dickinson 1984) and SiB 2 (Sellers et al. 1996). Evapotranspiration and runoff processes simulated by these models range from simple one-layer soils and no-vegetation parameterizations to complex multilayer soils, including realistic photosynthesis-stomatal conductance models. The latter is driven by satellite remote sensing land surface parameters inheriting the spatiotemporal evolution of vegetation phenology. In addition a simulation with SiB 2 not only including vertical water fluxes but also lateral soil moisture transfers by downslope flow is conducted for a pre-alpine catchment in Switzerland. Preliminary results are presented and show that - depending on the climatic environment and on the season - a realistic representation of evapotranspiration processes including seasonally and interannually-varying state of vegetation is significantly improving the representation of observed latent and sensible heat fluxes on the local scale. Moreover, the interannual evolution of soil moisture availability and runoff is strongly dependent on the chosen model complexity. Biophysical land surface parameters from satellite allow to represent the seasonal changes in vegetation activity, which has great impact on the yearly budget of transpiration fluxes. For some sites, however, the hydrological cycle is simulated reasonably well even with simple land surface representations.

BOREAS RSS-8 BIOME-BGC Model Simulations at Tower Flux Sites in 1994

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Nickeson, Jaime (Editor); Kimball, John

2000-01-01

BIOME-BGC is a general ecosystem process model designed to simulate biogeochemical and hydrologic processes across multiple scales (Running and Hunt, 1993). In this investigation, BIOME-BGC was used to estimate daily water and carbon budgets for the BOREAS tower flux sites for 1994. Carbon variables estimated by the model include gross primary production (i.e., net photosynthesis), maintenance and heterotrophic respiration, net primary production, and net ecosystem carbon exchange. Hydrologic variables estimated by the model include snowcover, evaporation, transpiration, evapotranspiration, soil moisture, and outflow. The information provided by the investigation includes input initialization and model output files for various sites in tabular ASCII format.

Multiscale characterization and mechanical modeling of an Al-Zn-Mg electron beam weld

NASA Astrophysics Data System (ADS)

Puydt, Quentin; Flouriot, Sylvain; Ringeval, Sylvain; Parry, Guillaume; De Geuser, Frédéric; Deschamps, Alexis

Welding of precipitation hardening alloys results in multi-scale microstructural heterogeneities, from the hardening nano-scale precipitates to the micron-scale solidification structures and to the component geometry. This heterogeneity results in a complex mechanical response, with gradients in strength, stress triaxiality and damage initiation sites.

Novel Sensor for the In Situ Measurement of Uranium Fluxes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatfield, Kirk

2015-02-10

The goal of this project was to develop a sensor that incorporates the field-tested concepts of the passive flux meter to provide direct in situ measures of flux for uranium and groundwater in porous media. Measurable contaminant fluxes [J] are essentially the product of concentration [C] and groundwater flux or specific discharge [q ]. The sensor measures [J] and [q] by changes in contaminant and tracer amounts respectively on a sorbent. By using measurement rather than inference from static parameters, the sensor can directly advance conceptual and computational models for field scale simulations. The sensor was deployed in conjunction withmore » DOE in obtaining field-scale quantification of subsurface processes affecting uranium transport (e.g., advection) and transformation (e.g., uranium attenuation) at the Rifle IFRC Site in Rifle, Colorado. Project results have expanded our current understanding of how field-scale spatial variations in fluxes of uranium, groundwater and salient electron donor/acceptors are coupled to spatial variations in measured microbial biomass/community composition, effective field-scale uranium mass balances, attenuation, and stability. The coupling between uranium, various nutrients and micro flora can be used to estimate field-scale rates of uranium attenuation and field-scale transitions in microbial communities. This research focuses on uranium (VI), but the sensor principles and design are applicable to field-scale fate and transport of other radionuclides. Laboratory studies focused on sorbent selection and calibration, along with sensor development and validation under controlled conditions. Field studies were conducted at the Rifle IFRC Site in Rifle, Colorado. These studies were closely coordinated with existing SBR (formerly ERSP) projects to complement data collection. Small field tests were conducted during the first two years that focused on evaluating field-scale deployment procedures and validating sensor performance under controlled field conditions. In the third and fourth year a suite of larger field studies were conducted. For these studies, the uranium flux sensor was used with uranium speciation measurements and molecular-biological tools to characterize microbial community and active biomass at synonymous wells distributed in a large grid. These field efforts quantified spatial changes in uranium flux and field-scale rates of uranium attenuation (ambient and stimulated), uranium stability, and quantitatively assessed how fluxes and effective reaction rates were coupled to spatial variations in microbial community and active biomass. Analyses of data from these field experiments were used to generate estimates of Monod kinetic parameters that are ‘effective’ in nature and optimal for modeling uranium fate and transport at the field-scale. This project provided the opportunity to develop the first sensor that provides direct measures of both uranium (VI) and groundwater flux. A multidisciplinary team was assembled to include two geochemists, a microbiologist, and two quantitative contaminant hydrologists. Now that the project is complete, the sensor can be deployed at DOE sites to evaluate field-scale uranium attenuation, source behavior, the efficacy of remediation, and off-site risk. Because the sensor requires no power, it can be deployed at remote sites for periods of days to months. The fundamental science derived from this project can be used to advance the development of predictive models for various transport and attenuation processes in aquifers. Proper development of these models is critical for long-term stewardship of contaminated sites in the context of predicting uranium source behavior, remediation performance, and off-site risk.« less

Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States

Treesearch

Xueri Dang; Chun-Ta Lai; David Y. Hollinger; Andrew J. Schauer; Jingfeng Xiao; J. William Munger; Clenton Owensby; James R. Ehleringer

2011-01-01

We evaluated an idealized boundary layer (BL) model with simple parameterizations using vertical transport information from community model outputs (NCAR/NCEP Reanalysis and ECMWF Interim Analysis) to estimate regional-scale net CO2 fluxes from 2002 to 2007 at three forest and one grassland flux sites in the United States. The BL modeling...

Prospective Creation and Validation of the PREVENTT (Prediction and Enaction of Prevention Treatments Trigger) Scale for Surgical Site Infections (SSIs) in Patients With Diverticulitis.

PubMed

Bordeianou, Liliana; Cauley, Christy E; Patel, Ruchin; Bleday, Ronald; Mahmood, Sadiqa; Kennedy, Kevin; Ahmed, Khawaja F; Yokoe, Deborah; Hooper, David; Rubin, Marc

2018-06-18

Create and validate diverticulitis surgical site infection prediction scale. Surgical site infections cause significant morbidity after colorectal surgery. An infection prediction scale could target infection prevention bundles to high-risk patients. Prospectively collected National Surgical Quality Improvement Program and electronic medical record data obtained on diverticulitis colectomy patients across a Healthcare Network-wide Colorectal Surgery Collaborative (5 hospitals). Patients with and without surgical site infections were compared. Predictive variables were identified using logistic regression model; model estimates obtained through 1000 bootstrap replications for scale validation. A total of 1737 colectomies were performed (2010-2016): mean age 59.9 years (SD 12.7), 56.4% female; 93.4% Caucasian; smokers 16.3%, diabetics 7.7%, steroid use 6.0%. Two hundred thirty-one (13.3%) were presented to operating room emergently and 138 (7.9%) with abscess at time of disease admission. Two hundred ninety-six patients underwent Hartman procedures, and 113 (6.5%) received diverted primary anastomosis. Average length of stay was 6.9 days (standard deviation 7.01), 30-day mortality was 1.5%, anastomotic leak rate was 3.1%. Twenty-one percent of patients (n = 366) developed a surgical site infection. Several predictors for infection were identified: obesity (body mass index >30), advanced age (>70 years), diabetes mellitus, preoperative abscess, open surgery, emergent operations, and prolonged operations (>3 h). Creation of protected anastomosis in emergent settings was associated with increased infection rates. Presence of more than 5 risk factors was associated with infection rates of 45.8% (c = 0.69). Patients with diverticulitis have high surgical site infection rates due to nonmodifiable risk factors. Our Prediction and Enaction of Prevention Treatments Trigger scale can risk stratify patients for targeting surgical site infection prevention bundles and outcomes risk adjustments.

Basins of attraction of the bistable region of time-delayed cutting dynamics

NASA Astrophysics Data System (ADS)

Yan, Yao; Xu, Jian; Wiercigroch, Marian

2017-09-01

This paper investigates the effects of bistability in a nonsmooth time-delayed dynamical system, which is often manifested in science and engineering. Previous studies on cutting dynamics have demonstrated persistent coexistence of chatter and chatter-free responses in a bistable region located in the linearly stable zone. As there is no widely accepted definition of basins of attraction for time-delayed systems, bistable regions are coined as unsafe zones (UZs). Hence, we have attempted to define the basins of attraction and stability basins for a typical delayed system to get insight into the bistability in systems with time delays. Special attention was paid to the influences of delayed initial conditions, starting points, and states at time zero on the long-term dynamics of time-delayed systems. By using this concept, it has been confirmed that the chatter is prone to occur when the waviness frequency in the workpiece surface coincides with the effective natural frequency of the cutting process. Further investigations unveil a thin "boundary layer" inside the UZ in the immediate vicinity of the stability boundary, in which we observe an extremely fast growth of the chatter basin stability. The results reveal that the system is more stable when the initial cutting depth is smaller. The physics of the tool deflection at the instant of the tool-workpiece engagement is used to evaluate the cutting safety, and the safe level could be zero when the geometry of tool engagement is unfavorable. Finally, the basins of attraction are used to quench the chatter by a single strike, where the resultant "islands" offer an opportunity to suppress the chatter even when the cutting is very close to the stability boundary.

The Equatorial Coordinates and B-Magnitudes of the Stars in the Southern Hemisphere Zones Based on the Digitized Astronegatives of FON Project at the Ulugh Beg Astronomical Institute

NASA Astrophysics Data System (ADS)

Yuldoshev, Q. X.; Muminov, M. M.; Ehgamberdiev, Sh. A.; Usmanov, O. U.; Relke, H.; Protsyuk, Yu. I.; Kovylianska, O. E.; Protsyuk, S. V.; Andruk, V. N.

FON (Russian abbreviation of the Photographic Sky Survey) were carried out at 6 observatories. The Kitab Observatory (KO) of Ulugh Beg Astronomical Institute (UBAI) of the Uzbek Academy of Sciences (UzAS) was involved in this project from 1981 to 1996. For the observations the Double Astrograph of Zeiss (DAZ, D/F = 40/300, 69"/mm) was used. On the FON project about 2600 photographic plates were exposed. In October, 2015 digitization of these astroplates were started using EPSON Expression 10000XL flatbed scanner with the spatial resolution of 1200 dpi and completed in June, 2016. The first stage of the work is the processing of the 2000 photographic plates in zones of the southern hemisphere with the declination between 0 and -20 degrees. The 1704 plates have already been processed. The equatorial coordinates α, δ of stars and galaxies were determined in the system of the Tycho2 catalogue and the Bmagnitudes in the system of the photoelectric standards. UBAI UzAS, Tashkent (Uzbekistan), ASU, Andijan (Uzbekistan), WHO, Essen (Germany), RI NAO, Nikolaev (Ukraine), MAO NASU, Kyiv (Ukraine) have taken part in the processing of the digitized images. For the data reduction the MIDAS package and software, developed in the MAO NASU were used. Based on the results of the processing of the astronegatives in the sectors of right ascension from 0 hours to 24 hours and declination from - 20° to 0° the internal errors of the catalogue were estimated. The errors calculated for all stars are 0.17" and 0.18m respectively. For the stars brighter than 14 magnitude the errors are 0.08" and 0.07m for the equatorial coordinates and B-magnitudes respectively.

A three-site gauge model for flavor hierarchies and flavor anomalies

NASA Astrophysics Data System (ADS)

Bordone, Marzia; Cornella, Claudia; Fuentes-Martín, Javier; Isidori, Gino

2018-04-01

We present a three-site Pati-Salam gauge model able to explain the Standard Model flavor hierarchies while, at the same time, accommodating the recent experimental hints of lepton-flavor non-universality in B decays. The model is consistent with low- and high-energy bounds, and predicts a rich spectrum of new states at the TeV scale that could be probed in the near future by the high-pT experiments at the LHC.

Posttest analysis of the 1:6-scale reinforced concrete containment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfeiffer, P.A.; Kennedy, J.M.; Marchertas, A.H.

A prediction of the response of the Sandia National Laboratories 1:6- scale reinforced concrete containment model test was made by Argonne National Laboratory. ANL along with nine other organizations performed a detailed nonlinear response analysis of the 1:6-scale model containment subjected to overpressurization in the fall of 1986. The two-dimensional code TEMP-STRESS and the three-dimensional NEPTUNE code were utilized (1) to predict the global response of the structure, (2) to identify global failure sites and the corresponding failure pressures and (3) to identify some local failure sites and pressure levels. A series of axisymmetric models was studied with the two-dimensionalmore » computer program TEMP-STRESS. The comparison of these pretest computations with test data from the containment model has provided a test for the capability of the respective finite element codes to predict global failure modes, and hence serves as a validation of these codes. Only the two-dimensional analyses will be discussed in this paper. 3 refs., 10 figs.« less

Computer 3D site model generation based on aerial images

NASA Astrophysics Data System (ADS)

Zheltov, Sergey Y.; Blokhinov, Yuri B.; Stepanov, Alexander A.; Skryabin, Sergei V.; Sibiriakov, Alexandre V.

1997-07-01

The technology for 3D model design of real world scenes and its photorealistic rendering are current topics of investigation. Development of such technology is very attractive to implement in vast varieties of applications: military mission planning, crew training, civil engineering, architecture, virtual reality entertainments--just a few were mentioned. 3D photorealistic models of urban areas are often discussed now as upgrade from existing 2D geographic information systems. Possibility of site model generation with small details depends on two main factors: available source dataset and computer power resources. In this paper PC based technology is presented, so the scenes of middle resolution (scale of 1:1000) be constructed. Types of datasets are the gray level aerial stereo pairs of photographs (scale of 1:14000) and true color on ground photographs of buildings (scale ca.1:1000). True color terrestrial photographs are also necessary for photorealistic rendering, that in high extent improves human perception of the scene.

One way coupling of CMAQ and a road source dispersion model for fine scale air pollution predictions

PubMed Central

Beevers, Sean D.; Kitwiroon, Nutthida; Williams, Martin L.; Carslaw, David C.

2012-01-01

In this paper we have coupled the CMAQ and ADMS air quality models to predict hourly concentrations of NOX, NO2 and O3 for London at a spatial scale of 20 m × 20 m. Model evaluation has demonstrated reasonable agreement with measurements from 80 monitoring sites in London. For NO2 the model evaluation statistics gave 73% of the hourly concentrations within a factor of two of observations, a mean bias of −4.7 ppb and normalised mean bias of −0.17, a RMSE value of 17.7 and an r value of 0.58. The equivalent results for O3 were 61% (FAC2), 2.8 ppb (MB), 0.15 (NMB), 12.1 (RMSE) and 0.64 (r). Analysis of the errors in the model predictions by hour of the week showed the need for improvements in predicting the magnitude of road transport related NOX emissions as well as the hourly emissions scaling in the model. These findings are consistent with recent evidence of UK road transport NOX emissions, reported elsewhere. The predictions of wind speed using the WRF model also influenced the model results and contributed to the daytime over prediction of NOX concentrations at the central London background site at Kensington and Chelsea. An investigation of the use of a simple NO–NO2–O3 chemistry scheme showed good performance close to road sources, and this is also consistent with previous studies. The coupling of the two models raises an issue of emissions double counting. Here, we have put forward a pragmatic solution to this problem with the result that a median double counting error of 0.42% exists across 39 roadside sites in London. Finally, whilst the model can be improved, the current results show promise and demonstrate that the use of a combination of regional scale and local scale models can provide a practical modelling tool for policy development at intergovernmental, national and local authority level, as well as for use in epidemiological studies. PMID:23471172

Measuring the patient perspective on latissimus dorsi donor site outcomes following breast reconstruction.

PubMed

Browne, John P; Jeevan, Ranjeet; Pusic, Andrea L; Klassen, Anne F; Gulliver-Clarke, Carmel; Pereira, Jerome; Caddy, Christopher M; Cano, Stefan J

2018-03-01

There is little evidence about the long-term donor site outcome of latissimus dorsi breast reconstruction and no patient-reported outcome measures designed specifically for the procedure. A prospective cohort of breast cancer patients having latissimus dorsi reconstruction after a mastectomy was recruited from 270 hospitals in the United Kingdom. An 18-month follow up questionnaire containing two novel scales was sent to consenting patients. The prevalence of aesthetic and functional morbidity at the donor site was described. The two new scales were refined using the Rasch measurement model and subsequently validated. 1,096 women completed the new scales. 78% of patients reported that no back appearance issues had bothered them "most of the time" or "all of the time" in the past two weeks. The equivalent figure for functional morbidity was 60%. Four items were eliminated following initial psychometric testing. This produced an 8-item Back Appearance scale and an 11-item Back and Shoulder Function scale. Both scales showed adequate fit to the Rasch measurement model. Higher levels of aesthetic and functional bother were observed for completely autologous procedures versus those where latissimus dorsi reconstruction was used to cover an implant (p <0.05). Higher levels of aesthetic bother were observed in women who had suffered a perioperative complication at the donor site (p = 0.003). These results can inform patients of the morbidity associated with latissimus dorsi reconstruction. The new scales can be used to compare groups undergoing different variations of the procedure and to monitor individual patients. Copyright © 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Green Infrastructure Modeling Tools

EPA Pesticide Factsheets

Modeling tools support planning and design decisions on a range of scales from setting a green infrastructure target for an entire watershed to designing a green infrastructure practice for a particular site.

Reduced-complexity multi-site rainfall generation: one million years over night using the model TripleM

NASA Astrophysics Data System (ADS)

Breinl, Korbinian; Di Baldassarre, Giuliano; Girons Lopez, Marc

2017-04-01

We assess uncertainties of multi-site rainfall generation across spatial scales and different climatic conditions. Many research subjects in earth sciences such as floods, droughts or water balance simulations require the generation of long rainfall time series. In large study areas the simulation at multiple sites becomes indispensable to account for the spatial rainfall variability, but becomes more complex compared to a single site due to the intermittent nature of rainfall. Weather generators can be used for extrapolating rainfall time series, and various models have been presented in the literature. Even though the large majority of multi-site rainfall generators is based on similar methods, such as resampling techniques or Markovian processes, they often become too complex. We think that this complexity has been a limit for the application of such tools. Furthermore, the majority of multi-site rainfall generators found in the literature are either not publicly available or intended for being applied at small geographical scales, often only in temperate climates. Here we present a revised, and now publicly available, version of a multi-site rainfall generation code first applied in 2014 in Austria and France, which we call TripleM (Multisite Markov Model). We test this fast and robust code with daily rainfall observations from the United States, in a subtropical, tropical and temperate climate, using rain gauge networks with a maximum site distance above 1,000km, thereby generating one million years of synthetic time series. The modelling of these one million years takes one night on a recent desktop computer. In this research, we first start the simulations with a small station network of three sites and progressively increase the number of sites and the spatial extent, and analyze the changing uncertainties for multiple statistical metrics such as dry and wet spells, rainfall autocorrelation, lagged cross correlations and the inter-annual rainfall variability. Our study contributes to the scientific community of earth sciences and the ongoing debate on extreme precipitation in a changing climate by making a stable, and very easily applicable, multi-site rainfall generation code available to the research community and providing a better understanding of the performance of multi-site rainfall generation depending on spatial scales and climatic conditions.

JWST Full-Scale Model on Display at Goddard Space Flight Center

NASA Image and Video Library

2010-02-26

JWST Full-Scale Model on Display. A full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite. The model is constructed mainly of aluminum and steel, weighs 12,000 lb., and is approximately 80 feet long, 40 feet wide and 40 feet tall. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. This model has travelled to a few sites since 2005. The photographs below were taken at some of its destinations. The model is pictured here in Greenbelt, MD at the NASA Goddard Space Flight Center. Credit: NASA/Goddard Space Flight Center/Pat Izzo

Evaluation of spatial models to predict vulnerability of forest birds to brood parasitism by cowbirds

USGS Publications Warehouse

Gustafson, E.J.; Knutson, M.G.; Niemi, G.J.; Friberg, M.

2002-01-01

We constructed alternative spatial models at two scales to predict Brown-headed Cowbird (Molothrus ater) parasitism rates from land cover maps. The local-scale models tested competing hypotheses about the relationship between cowbird parasitism and distance of host nests from a forest edge (forest-nonforest boundary). The landscape models tested competing hypotheses about how landscape features (e.g., forests, agricultural fields) interact to determine rates of cowbird parasitism. The models incorporate spatial neighborhoods with a radius of 2.5 km in their formulation, reflecting the scale of the majority of cowbird commuting activity. Field data on parasitism by cowbirds (parasitism rate and number of cowbird eggs per nest) were collected at 28 sites in the Driftless Area Ecoregion of Wisconsin, Minnesota, and Iowa and were compared to the predictions of the alternative models. At the local scale, there was a significant positive relationship between cowbird parasitism and mean distance of nest sites from the forest edge. At the landscape scale, the best fitting models were the forest-dependent and forest-fragmentation-dependent models, in which more heavily forested and less fragmented landscapes had higher parasitism rates. However, much of the explanatory power of these models results from the inclusion of the local-scale relationship in these models. We found lower rates of cowbird parasitism than did most Midwestern studies, and we identified landscape patterns of cowbird parasitism that are opposite to those reported in several other studies of Midwestern songbirds. We caution that cowbird parasitism patterns can be unpredictable, depending upon ecoregional location and the spatial extent, and that our models should be tested in other ecoregions before they are applied there. Our study confirms that cowbird biology has a strong spatial component, and that improved spatial models applied at multiple spatial scales will be required to predict the effects of landscape and forest management on cowbird parasitism of forest birds.

Reactive transport of uranium in fractured crystalline rock: Upscaling in time and distance

DOE PAGES

Dittrich, Timothy M.; Reimus, Paul W.

2015-09-29

In this study, batch adsorption and breakthrough column experiments were conducted to evaluate uranium transport through altered material that fills fractures in a granite rock system at the Grimsel Test Site in Switzerland at pH 6.9 and 7.9. The role of adsorption and desorption kinetics was evaluated with reactive transport modeling by comparing one-, two-, and three-site models. Emphasis was placed on describing long desorption tails that are important for upscaling in time and distance. The effect of increasing pH in injection solutions was also evaluated. For pH 6.9, a three-site model with forward rate constants between 0.07 and 0.8more » ml g –1 h –1, reverse rate constants between 0.001 and 0.06 h –1, and site densities of 1.3, 0.104, and 0.026 μmol g –1 for ‘weak/fast’, ‘strong/slow’, and ‘very strong/very slow’ sites provided the best fits. For pH 7.9, a three-site model with forward rate constants between 0.05 and 0.8 mL g –1 h –1, reverse rate constants between 0.001 and 0.6 h –1, and site densities of 1.3, 0.039, and 0.013 μmol g –1 for a ‘weak/fast’, ‘strong/slow’, and ‘very strong/very slow’ sites provided the best fits. Column retardation coefficients (R d) were 80 for pH 6.9 and 10.3 for pH 7.9. Model parameters determined from the batch and column experiments were used in 50 year large-scale simulations for continuous and pulse injections and indicated that a three-site model is necessary at pH 6.9, although a K d-type equilibrium partition model with one-site was adequate for large scale predictions at pH 7.9. Batch experiments were useful for predicting early breakthrough times in the columns while column experiments helped differentiate the relative importance of sorption sites and desorption rate constants on transport.« less

Local Scale Radiobrightness Modeling During the Intensive Observing Period-4 of the Cold Land Processes Experiment-1

NASA Astrophysics Data System (ADS)

Kim, E.; Tedesco, M.; de Roo, R.; England, A. W.; Gu, H.; Pham, H.; Boprie, D.; Graf, T.; Koike, T.; Armstrong, R.; Brodzik, M.; Hardy, J.; Cline, D.

2004-12-01

The NASA Cold Land Processes Field Experiment (CLPX-1) was designed to provide microwave remote sensing observations and ground truth for studies of snow and frozen ground remote sensing, particularly issues related to scaling. CLPX-1 was conducted in 2002 and 2003 in Colorado, USA. One of the goals of the experiment was to test the capabilities of microwave emission models at different scales. Initial forward model validation work has concentrated on the Local-Scale Observation Site (LSOS), a 0.8~ha study site consisting of open meadows separated by trees where the most detailed measurements were made of snow depth and temperature, density, and grain size profiles. Results obtained in the case of the 3rd Intensive Observing Period (IOP3) period (February, 2003, dry snow) suggest that a model based on Dense Medium Radiative Transfer (DMRT) theory is able to model the recorded brightness temperatures using snow parameters derived from field measurements. This paper focuses on the ability of forward DMRT modelling, combined with snowpack measurements, to reproduce the radiobrightness signatures observed by the University of Michigan's Truck-Mounted Radiometer System (TMRS) at 19 and 37~GHz during the 4th IOP (IOP4) in March, 2003. Unlike in IOP3, conditions during IOP4 include both wet and dry periods, providing a valuable test of DMRT model performance. In addition, a comparison will be made for the one day of coincident observations by the University of Tokyo's Ground-Based Microwave Radiometer-7 (GBMR-7) and the TMRS. The plot-scale study in this paper establishes a baseline of DMRT performance for later studies at successively larger scales. And these scaling studies will help guide the choice of future snow retrieval algorithms and the design of future Cold Lands observing systems.

Probabilistic inference of ecohydrological parameters using observations from point to satellite scales

NASA Astrophysics Data System (ADS)

Bassiouni, Maoya; Higgins, Chad W.; Still, Christopher J.; Good, Stephen P.

2018-06-01

Vegetation controls on soil moisture dynamics are challenging to measure and translate into scale- and site-specific ecohydrological parameters for simple soil water balance models. We hypothesize that empirical probability density functions (pdfs) of relative soil moisture or soil saturation encode sufficient information to determine these ecohydrological parameters. Further, these parameters can be estimated through inverse modeling of the analytical equation for soil saturation pdfs, derived from the commonly used stochastic soil water balance framework. We developed a generalizable Bayesian inference framework to estimate ecohydrological parameters consistent with empirical soil saturation pdfs derived from observations at point, footprint, and satellite scales. We applied the inference method to four sites with different land cover and climate assuming (i) an annual rainfall pattern and (ii) a wet season rainfall pattern with a dry season of negligible rainfall. The Nash-Sutcliffe efficiencies of the analytical model's fit to soil observations ranged from 0.89 to 0.99. The coefficient of variation of posterior parameter distributions ranged from < 1 to 15 %. The parameter identifiability was not significantly improved in the more complex seasonal model; however, small differences in parameter values indicate that the annual model may have absorbed dry season dynamics. Parameter estimates were most constrained for scales and locations at which soil water dynamics are more sensitive to the fitted ecohydrological parameters of interest. In these cases, model inversion converged more slowly but ultimately provided better goodness of fit and lower uncertainty. Results were robust using as few as 100 daily observations randomly sampled from the full records, demonstrating the advantage of analyzing soil saturation pdfs instead of time series to estimate ecohydrological parameters from sparse records. Our work combines modeling and empirical approaches in ecohydrology and provides a simple framework to obtain scale- and site-specific analytical descriptions of soil moisture dynamics consistent with soil moisture observations.

Large Scale Ice Water Path and 3-D Ice Water Content

DOE Data Explorer

Liu, Guosheng

2008-01-15

Cloud ice water concentration is one of the most important, yet poorly observed, cloud properties. Developing physical parameterizations used in general circulation models through single-column modeling is one of the key foci of the ARM program. In addition to the vertical profiles of temperature, water vapor and condensed water at the model grids, large-scale horizontal advective tendencies of these variables are also required as forcing terms in the single-column models. Observed horizontal advection of condensed water has not been available because the radar/lidar/radiometer observations at the ARM site are single-point measurement, therefore, do not provide horizontal distribution of condensed water. The intention of this product is to provide large-scale distribution of cloud ice water by merging available surface and satellite measurements. The satellite cloud ice water algorithm uses ARM ground-based measurements as baseline, produces datasets for 3-D cloud ice water distributions in a 10 deg x 10 deg area near ARM site. The approach of the study is to expand a (surface) point measurement to an (satellite) areal measurement. That is, this study takes the advantage of the high quality cloud measurements at the point of ARM site. We use the cloud characteristics derived from the point measurement to guide/constrain satellite retrieval, then use the satellite algorithm to derive the cloud ice water distributions within an area, i.e., 10 deg x 10 deg centered at ARM site.

Measurement of Global Radiation using Photovoltaic Panels

NASA Astrophysics Data System (ADS)

Veroustraete, Frank; Bronders, Jan; Lefevre, Filip; Mensink, Clemens

2014-05-01

The Vito Unit - Environmental and Spatial Aspects (RMA) - for many of its models makes use of global solar radiation. From this viewpoint and also from the notion that this variable is seldom measured or available at the local scale and at high multi-temporal frequencies, it can be stated that many models are fed with low quality estimates of global solar radiation at the local to regional scales. A project was initiated called SUNSPIDER with the following objective. To make use of photovoltaic solar panels to measure solar radiation at the highest spatio-temporal resolution, from the local to the regional scales and from minutes to years. To integrate the measured solar fields in different application fields like, plant systems and agriculture, agro-meteorology and hydrology and last but not least solar energy applications. In Belgium about 250.000 PV installations have been built leading to about 6% electric power supply from photovoltaics on a yearly basis. Last year in June, the supply reached a peak of more than 20% of the total power input on the Belgian grid. A database of Belgian residential solar panel sites will be compiled. The database will serve as an input to an inverted PV model to be able to perform radiation calculations specifically for each of the validated panel sites based on minutely logged power data. Data acquisition for these sites will start each time a site is validated and hence imported in the database. Keywords: Photovoltaic Panels; PV modelling; Global Radiation.

Fire rehabilitation decisions at landscape scales: utilizing state-and-transition models developed through disturbance response grouping of ecological sites

USDA-ARS?s Scientific Manuscript database

Recognizing the utility of ecological sites and the associated state-and-transition model (STM) for decision support, the Bureau of Land Management in Nevada partnered with Nevada NRCS and the University of Nevada, Reno (UNR) in 2009 with the goal of creating a team that could (1) expedite developme...

An Integrated Assessment of Location-Dependent Scaling for Microalgae Biofuel Production Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, Andre M.; Abodeely, Jared; Skaggs, Richard

Successful development of a large-scale microalgae-based biofuels industry requires comprehensive analysis and understanding of the feedstock supply chain—from facility siting/design through processing/upgrading of the feedstock to a fuel product. The evolution from pilot-scale production facilities to energy-scale operations presents many multi-disciplinary challenges, including a sustainable supply of water and nutrients, operational and infrastructure logistics, and economic competitiveness with petroleum-based fuels. These challenges are addressed in part by applying the Integrated Assessment Framework (IAF)—an integrated multi-scale modeling, analysis, and data management suite—to address key issues in developing and operating an open-pond facility by analyzing how variability and uncertainty in space andmore » time affect algal feedstock production rates, and determining the site-specific “optimum” facility scale to minimize capital and operational expenses. This approach explicitly and systematically assesses the interdependence of biofuel production potential, associated resource requirements, and production system design trade-offs. The IAF was applied to a set of sites previously identified as having the potential to cumulatively produce 5 billion-gallons/year in the southeastern U.S. and results indicate costs can be reduced by selecting the most effective processing technology pathway and scaling downstream processing capabilities to fit site-specific growing conditions, available resources, and algal strains.« less

Disentangling Climate and Land-use Impacts on Grassland Carbon and Water Fluxes

NASA Astrophysics Data System (ADS)

Brunsell, N. A.; Nippert, J. B.

2014-12-01

Regional climate and land cover interact in a complex, non-linear manner to alter the local cycling of mass and energy. It is often difficult to isolate the role of either mechanism on the resultant fluxes. Here, we attempt to isolate these mechanisms through the use of network of 4 Ameriflux eddy covariance towers installed over different land cover and land use classes along a pronounced rainfall gradient. The land cover types include: annually burned C4 grassland, a 4 year burn site experiencing woody encroachment, an abandoned agricultural field and a new perennial agricultural site. We investigated the impact of rainfall variability, drought, and heat waves on the water and carbon budgets using data analysis, remote sensing, and modeling approaches. In addition, we have established a network of mini-meteorological stations at the annually and 4-year burn sites to assess micro-scale variability within the footprints of the towers as a function of topographic position, soil depth and soil water availability. Through the use of a wavelet multiscale decomposition and information theory metrics, we have isolated the role of environmental factors (temperature, humidity, soil moisture, etc.) on the fluxes across the different sites. By applying a similar analysis to model output, we can assess the ability of land-surface models to recreate the observed sensitity. Results indicate the utility of a network of measurement systems used in conjunction with land surface modeling and time series analysis to assess differential impacts to similar regional scale climate forcings. Implications for the role of land cover class in regional and global scale modeling systems will also be discussed.

Inference of directional selection and mutation parameters assuming equilibrium.

PubMed

Vogl, Claus; Bergman, Juraj

2015-12-01

In a classical study, Wright (1931) proposed a model for the evolution of a biallelic locus under the influence of mutation, directional selection and drift. He derived the equilibrium distribution of the allelic proportion conditional on the scaled mutation rate, the mutation bias and the scaled strength of directional selection. The equilibrium distribution can be used for inference of these parameters with genome-wide datasets of "site frequency spectra" (SFS). Assuming that the scaled mutation rate is low, Wright's model can be approximated by a boundary-mutation model, where mutations are introduced into the population exclusively from sites fixed for the preferred or unpreferred allelic states. With the boundary-mutation model, inference can be partitioned: (i) the shape of the SFS distribution within the polymorphic region is determined by random drift and directional selection, but not by the mutation parameters, such that inference of the selection parameter relies exclusively on the polymorphic sites in the SFS; (ii) the mutation parameters can be inferred from the amount of polymorphic and monomorphic preferred and unpreferred alleles, conditional on the selection parameter. Herein, we derive maximum likelihood estimators for the mutation and selection parameters in equilibrium and apply the method to simulated SFS data as well as empirical data from a Madagascar population of Drosophila simulans. Copyright © 2015 Elsevier Inc. All rights reserved.

Modeling Stand-Scale Patterns in Evapotranspiration and Soil Moisture in a Heterogeneous Plant Canopy: A Coupled Subsurface-Land Surface Approach

NASA Astrophysics Data System (ADS)

Miller, G. R.; Gou, S.; Ferguson, I. M.; Maxwell, R. M.

2011-12-01

Savanna ecosystems present a well-known modeling challenge; understory grasses and overstory woody vegetation combine to form an open, heterogeneous canopy that creates strong spatial differences in soil moisture and evapotranspiration rates. In this analysis, we used ParFlow.CLM to create a stand-scale model of the Tonzi Ranch oak savanna, based on extensive topography, vegetation, soil, and hydrogeology data collected at the site. Measurements included canopy distribution and ground surface elevation from airborne Lidar, depth to groundwater from deep piezometers, soil and rock hydraulic conductivity, and leaf area index. We then compared the results to the site's long-term data records of radiative flux partitioning, obtained using the eddy-covariance method, and soil moisture, collected via a distributed network of capacitance probes. In order to obtain good agreement between the measured and modeled values, we identified several necessary modifications to the current CLM parameterization. These changes included the addition of a "winter grass" type and the alteration of the root structure and water stress functions to accommodate uptake of groundwater by deep roots. Finally, we compared variograms of site parameters and response variables and performed a scaling analysis relating ET and soil moisture variance to sampling size.

Regional Magnitude Research Supporting Broad-Area Monitoring of Small Seismic Events

DTIC Science & Technology

2007-09-01

detonated at the Nevada Test Site (NTS) and the Semipalatinsk Test Site (STS). Observations for both test sites show that Pn amplitudes yield scale 10...identification procedures, and yield, via direct comparison to test site results for high frequencies (>1 Hz). Coda techniques are known to be effective...2006). Source spectral modeling of regional P/S discriminants at nuclear test sites in China and the former Soviet Union, Bull. Seismol. Soc. Am

Meteorological Contribution to Variability in Particulate Matter Concentrations

NASA Astrophysics Data System (ADS)

Woods, H. L.; Spak, S. N.; Holloway, T.

2006-12-01

Local concentrations of fine particulate matter (PM) are driven by a number of processes, including emissions of aerosols and gaseous precursors, atmospheric chemistry, and meteorology at local, regional, and global scales. We apply statistical downscaling methods, typically used for regional climate analysis, to estimate the contribution of regional scale meteorology to PM mass concentration variability at a range of sites in the Upper Midwestern U.S. Multiple years of daily PM10 and PM2.5 data, reported by the U.S. Environmental Protection Agency (EPA), are correlated with large-scale meteorology over the region from the National Centers for Environmental Prediction (NCEP) reanalysis data. We use two statistical downscaling methods (multiple linear regression, MLR, and analog) to identify which processes have the greatest impact on aerosol concentration variability. Empirical Orthogonal Functions of the NCEP meteorological data are correlated with PM timeseries at measurement sites. We examine which meteorological variables exert the greatest influence on PM variability, and which sites exhibit the greatest response to regional meteorology. To evaluate model performance, measurement data are withheld for limited periods, and compared with model results. Preliminary results suggest that regional meteorological processes account over 50% of aerosol concentration variability at study sites.

A spatial scaling relationship for soil moisture in a semiarid landscape, using spatial scaling relationships for pedology

NASA Astrophysics Data System (ADS)

Willgoose, G. R.; Chen, M.; Cohen, S.; Saco, P. M.; Hancock, G. R.

2013-12-01

In humid areas it is generally considered that soil moisture scales spatially according to the wetness index of the landscape. This scaling arises from lateral flow downslope of ground water within the soil zone. However, in semi-arid and drier regions, this lateral flow is small and fluxes are dominated by vertical flows driven by infiltration and evapotranspiration. Thus, in the absence of runon processes, soil moisture at a location is more driven by local factors such as soil and vegetation properties at that location rather than upstream processes draining to that point. The 'apparent' spatial randomness of soil and vegetation properties generally suggests that soil moisture for semi-arid regions is spatially random. In this presentation a new analysis of neutron probe data during summer from the Tarrawarra site near Melbourne, Australia shows persistent spatial organisation of soil moisture over several years. This suggests a link between permanent features of the catchment (e.g. soil properties) and soil moisture distribution, even though the spatial pattern of soil moisture during the 4 summers monitored appears spatially random. This and other data establishes a prima facie case that soil variations drive spatial variation in soil moisture. Accordingly, we used a previously published spatial scaling relationship for soil properties derived using the mARM pedogenesis model to simulate the spatial variation of soil grading. This soil grading distribution was used in the Rosetta pedotransfer model to derive a spatial distribution of soil functional properties (e.g. saturated hydraulic conductivity, porosity). These functional properties were then input into the HYDRUS-1D soil moisture model and soil moisture simulated for 3 years at daily resolution. The HYDRUS model used had previously been calibrated to field observed soil moisture data at our SASMAS field site. The scaling behaviour of soil moisture derived from this modelling will be discussed and compared with observed data from our SASMAS field sites.

D Reconstruction and Visualization of Cultural Heritage: Analyzing Our Legacy Through Time

NASA Astrophysics Data System (ADS)

Rodríguez-Gonzálvez, P.; Muñoz-Nieto, A. L.; del Pozo, S.; Sanchez-Aparicio, L. J.; Gonzalez-Aguilera, D.; Micoli, L.; Gonizzi Barsanti, S.; Guidi, G.; Mills, J.; Fieber, K.; Haynes, I.; Hejmanowska, B.

2017-02-01

Temporal analyses and multi-temporal 3D reconstruction are fundamental for the preservation and maintenance of all forms of Cultural Heritage (CH) and are the basis for decisions related to interventions and promotion. Introducing the fourth dimension of time into three-dimensional geometric modelling of real data allows the creation of a multi-temporal representation of a site. In this way, scholars from various disciplines (surveyors, geologists, archaeologists, architects, philologists, etc.) are provided with a new set of tools and working methods to support the study of the evolution of heritage sites, both to develop hypotheses about the past and to model likely future developments. The capacity to "see" the dynamic evolution of CH assets across different spatial scales (e.g. building, site, city or territory) compressed in diachronic model, affords the possibility to better understand the present status of CH according to its history. However, there are numerous challenges in order to carry out 4D modelling and the requisite multi-data source integration. It is necessary to identify the specifications, needs and requirements of the CH community to understand the required levels of 4D model information. In this way, it is possible to determine the optimum material and technologies to be utilised at different CH scales, as well as the data management and visualization requirements. This manuscript aims to provide a comprehensive approach for CH time-varying representations, analysis and visualization across different working scales and environments: rural landscape, urban landscape and architectural scales. Within this aim, the different available metric data sources are systemized and evaluated in terms of their suitability.

Long-term lesser prairie-chicken nest ecology in response to grassland management

USGS Publications Warehouse

Fritts, Sarah R.; Grisham, Blake A.; Haukos, David A.; Boal, Clint W.; Patten, Michael; Wolfe, Don H.; Dixon, Charles; Cox, Robert D.; Heck, Willard R.

2016-01-01

Long-term population and range declines from habitat loss and fragmentation caused the lesser prairie-chicken (Tympanuchus pallidicinctus) to be a species of concern throughout its range. Current lesser prairie-chicken range in New Mexico and Texas is partially restricted to sand shinnery oak (Quercus havardii; hereafter shinnery oak) prairies, on which cattle grazing is the main socioeconomic driver for private landowners. Cattle producers within shinnery oak prairies often focus land management on shrub eradication using the herbicide tebuthiuron to promote grass production for forage; however, herbicide application alone, and in combination with grazing, may affect nest site selection and nest survival of lesser prairie-chickens through the reduction of shinnery oak and native grasses. We used a controlled, paired, completely randomized design study to assess the influence of grazing and tebuthiuron application and their combined use on nest site selection and nest survival from 2001 to 2010 in Roosevelt County, New Mexico, USA at 2 spatial scales (i.e., treatment and microhabitat) in 4 treatments: tebuthiuron with grazing, tebuthiuron without grazing, no tebuthiuron with grazing, and a control of no tebuthiuron and no grazing. Grazing treatment was a short-duration system in which plots were grazed once during the dormant season and once during the growing season. Stocking rate was calculated each season based on measured forage production and applied to remove ≤25% of available herbaceous material per season. At the treatment scale, we compared nest site selection among treatments using 1-way χ2 tests and nest survival among treatments using a priori candidate nest survival models in Program MARK. At the microhabitat scale, we identified important habitat predictors of nest site selection and nest survival using logistic regression and a priori candidate nest survival models in Program MARK, respectively. Females typically used treatments as expected and we did not detect trends in selection. Nest survival did not differ among treatments. At the microhabitat scale, nest sites had less bare ground (P = 0.001) and greater angles of obstruction (P ≤ 0.001) compared to random sites. There was a high degree of model selection uncertainty among our candidate models at the microhabitat scale and survival estimates were similar among habitat covariates. Results suggest a tebuthiuron application rate of 0.60 kg/ha, short-duration grazing, and a combination of these management techniques were not detrimental to lesser prairie-chicken nest site selection or nest survival. However, intensified management that increases bare ground or reduces overhead cover may negatively affect lesser prairie-chicken nesting habitat and nest survival.

The influence of model grid resolution on estimation of national scale nitrogen deposition and exceedance of critical levels

NASA Astrophysics Data System (ADS)

Dore, A. J.; Kryza, M.; Hall, J. R.; Hallsworth, S.; Keller, V. J. D.; Vieno, M.; Sutton, M. A.

2011-12-01

The Fine Resolution Atmospheric Multi-pollutant Exchange model (FRAME) has been applied to model the spatial distribution of nitrogen deposition and air concentration over the UK at a 1 km spatial resolution. The modelled deposition and concentration data were gridded at resolutions of 1 km, 5 km and 50 km to test the sensitivity of calculations of the exceedance of critical loads for nitrogen deposition to the deposition data resolution. The modelled concentrations of NO2 were validated by comparison with measurements from the rural sites in the national monitoring network and were found to achieve better agreement with the high resolution 1 km data. High resolution plots were found to represent a more physically realistic distribution of nitrogen air concentrations and deposition resulting from use of 1 km resolution precipitation and emissions data as compared to 5 km resolution data. Summary statistics for national scale exceedance of the critical load for nitrogen deposition were not highly sensitive to the grid resolution of the deposition data but did show greater area exceedance with coarser grid resolution due to spatial averaging of high nitrogen deposition hot spots. Local scale deposition at individual Sites of Special Scientific Interest and high precipitation upland sites was sensitive to choice of grid resolution of deposition data. Use of high resolution data tended to generate lower deposition values in sink areas for nitrogen dry deposition (Sites of Scientific Interest) and higher values in high precipitation upland areas. In areas with generally low exceedance (Scotland) and for certain vegetation types (montane), the exceedance statistics were more sensitive to model data resolution.

The influence of model grid resolution on estimation of national scale nitrogen deposition and exceedance of critical loads

NASA Astrophysics Data System (ADS)

Dore, A. J.; Kryza, M.; Hall, J. R.; Hallsworth, S.; Keller, V. J. D.; Vieno, M.; Sutton, M. A.

2012-05-01

The Fine Resolution Atmospheric Multi-pollutant Exchange model (FRAME) was applied to model the spatial distribution of reactive nitrogen deposition and air concentration over the United Kingdom at a 1 km spatial resolution. The modelled deposition and concentration data were gridded at resolutions of 1 km, 5 km and 50 km to test the sensitivity of calculations of the exceedance of critical loads for nitrogen deposition to the deposition data resolution. The modelled concentrations of NO2 were validated by comparison with measurements from the rural sites in the national monitoring network and were found to achieve better agreement with the high resolution 1 km data. High resolution plots were found to represent a more physically realistic distribution of reactive nitrogen air concentrations and deposition resulting from use of 1 km resolution precipitation and emissions data as compared to 5 km resolution data. Summary statistics for national scale exceedance of the critical load for nitrogen deposition were not highly sensitive to the grid resolution of the deposition data but did show greater area exceedance with coarser grid resolution due to spatial averaging of high nitrogen deposition hot spots. Local scale deposition at individual Sites of Special Scientific Interest and high precipitation upland sites was sensitive to choice of grid resolution of deposition data. Use of high resolution data tended to generate lower deposition values in sink areas for nitrogen dry deposition (Sites of Scientific Interest) and higher values in high precipitation upland areas. In areas with generally low exceedance (Scotland) and for certain vegetation types (montane), the exceedance statistics were more sensitive to model data resolution.

Financial management of a large multisite randomized clinical trial.

PubMed

Sheffet, Alice J; Flaxman, Linda; Tom, MeeLee; Hughes, Susan E; Longbottom, Mary E; Howard, Virginia J; Marler, John R; Brott, Thomas G

2014-08-01

The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) received five years' funding ($21 112 866) from the National Institutes of Health to compare carotid stenting to surgery for stroke prevention in 2500 randomized participants at 40 sites. Herein we evaluate the change in the CREST budget from a fixed to variable-cost model and recommend strategies for the financial management of large-scale clinical trials. Projections of the original grant's fixed-cost model were compared to the actual costs of the revised variable-cost model. The original grant's fixed-cost budget included salaries, fringe benefits, and other direct and indirect costs. For the variable-cost model, the costs were actual payments to the clinical sites and core centers based upon actual trial enrollment. We compared annual direct and indirect costs and per-patient cost for both the fixed and variable models. Differences between clinical site and core center expenditures were also calculated. Using a variable-cost budget for clinical sites, funding was extended by no-cost extension from five to eight years. Randomizing sites tripled from 34 to 109. Of the 2500 targeted sample size, 138 (5·5%) were randomized during the first five years and 1387 (55·5%) during the no-cost extension. The actual per-patient costs of the variable model were 9% ($13 845) of the projected per-patient costs ($152 992) of the fixed model. Performance-based budgets conserve funding, promote compliance, and allow for additional sites at modest additional cost. Costs of large-scale clinical trials can thus be reduced through effective management without compromising scientific integrity. © 2014 The Authors. International Journal of Stroke © 2014 World Stroke Organization.

Spatially explicit modelling of forest structure and function using airborne lidar and hyperspectral remote sensing data combined with micrometeorological measurements

NASA Astrophysics Data System (ADS)

Thomas, Valerie Anne

This research models canopy-scale photosynthesis at the Groundhog River Flux Site through the integration of high-resolution airborne remote sensing data and micrometeorological measurements collected from a flux tower. Light detection and ranging (lidar) data are analysed to derive models of tree structure, including: canopy height, basal area, crown closure, and average aboveground biomass. Lidar and hyperspectral remote sensing data are used to model canopy chlorophyll (Chl) and carotenoid concentrations (known to be good indicators of photosynthesis). The integration of lidar and hyperspectral data is applied to derive spatially explicit models of the fraction of photosynthetically active radiation (fPAR) absorbed by the canopy as well as a species classification for the site. These products are integrated with flux tower meteorological measurements (i.e., air temperature and global solar radiation) collected on a continuous basis over 2004 to apply the C-Fix model of carbon exchange to the site. Results demonstrate that high resolution lidar and lidar-hyperspectral integration techniques perform well in the boreal mixedwood environment. Lidar models are well correlated with forest structure, despite the complexities introduced in the mixedwood case (e.g., r2=0.84, 0.89, 0.60, and 0.91, for mean dominant height, basal area, crown closure, and average aboveground biomass). Strong relationships are also shown for canopy scale chlorophyll/carotenoid concentration analysis using integrated lidar-hyperspectral techniques (e.g., r2=0.84, 0.84, and 0.82 for Chl(a), Chl(a+b), and Chl(b)). Examination of the spatially explicit models of fPAR reveal distinct spatial patterns which become increasingly apparent throughout the season due to the variation in species groupings (and canopy chlorophyll concentration) within the 1 km radius surrounding the flux tower. Comparison of results from the modified local-scale version of the C-Fix model to tower gross ecosystem productivity (GEP) demonstrate a good correlation to flux tower measured GEP (r2=0.70 for 10 day averages), with the largest deviations occurring in June-July. This research has direct benefits for forest inventory mapping and management practices; mapping of canopy physiology and biochemical constituents related to forest health; and scaling and direct comparison to large resolution satellite models to help bridge the gap between the local-scale measurements at flux towers and predictions derived from continental-scale carbon models.

Genome-scale dynamic modeling of the competition between Rhodoferax and Geobacter in anoxic subsurface environments.

PubMed

Zhuang, Kai; Izallalen, Mounir; Mouser, Paula; Richter, Hanno; Risso, Carla; Mahadevan, Radhakrishnan; Lovley, Derek R

2011-02-01

The advent of rapid complete genome sequencing, and the potential to capture this information in genome-scale metabolic models, provide the possibility of comprehensively modeling microbial community interactions. For example, Rhodoferax and Geobacter species are acetate-oxidizing Fe(III)-reducers that compete in anoxic subsurface environments and this competition may have an influence on the in situ bioremediation of uranium-contaminated groundwater. Therefore, genome-scale models of Geobacter sulfurreducens and Rhodoferax ferrireducens were used to evaluate how Geobacter and Rhodoferax species might compete under diverse conditions found in a uranium-contaminated aquifer in Rifle, CO. The model predicted that at the low rates of acetate flux expected under natural conditions at the site, Rhodoferax will outcompete Geobacter as long as sufficient ammonium is available. The model also predicted that when high concentrations of acetate are added during in situ bioremediation, Geobacter species would predominate, consistent with field-scale observations. This can be attributed to the higher expected growth yields of Rhodoferax and the ability of Geobacter to fix nitrogen. The modeling predicted relative proportions of Geobacter and Rhodoferax in geochemically distinct zones of the Rifle site that were comparable to those that were previously documented with molecular techniques. The model also predicted that under nitrogen fixation, higher carbon and electron fluxes would be diverted toward respiration rather than biomass formation in Geobacter, providing a potential explanation for enhanced in situ U(VI) reduction in low-ammonium zones. These results show that genome-scale modeling can be a useful tool for predicting microbial interactions in subsurface environments and shows promise for designing bioremediation strategies.

Improving UK Chalk hydrometeorology across spatial scales using a small hydrometeorological network

NASA Astrophysics Data System (ADS)

Rosolem, Rafael; Iwema, Joost; Rahman, Mostaquimur; Desilets, Darin; Koltermann da Silva, Juliana

2016-04-01

Chalk in the UK acts as a primary aquifer providing up to 80% of the public water supply locally. Chalk outcrops are located over most of southern and eastern England. Despite its importance, the characterization of Chalk in hydrometeorological models is still very limited. There is a need for a comprehensive and coherent integration of observations and modeling efforts across spatial scales for better understanding Chalk hydrometeorology. Here we introduce the "A MUlti-scale Soil moisture-Evapotranspiration Dynamics" (AMUSED) project. AMUSED goal is to better identify the key dominant processes controlling changes in soil moisture and surface fluxes (e.g., evapotranspiration) across spatial scales by combining ground-based observations with hydrometeorological models and satellite remote sensing products. The AMUSED observational platform consists of three sites located in Upper Chalk region of the Lambourn Catchment located in southern England covering approximately 2 square-km characterized by distinct combinations of soil and vegetation types. The network includes standard meteorological measurements, an eddy covariance system for turbulent fluxes and cosmic-ray neutron sensors for integrated soil moisture estimates at intermediate scales. Here we present our initial results from our three sites.

Downscaling near-surface soil moisture from field to plot scale: A comparative analysis under different environmental conditions

NASA Astrophysics Data System (ADS)

Nasta, Paolo; Penna, Daniele; Brocca, Luca; Zuecco, Giulia; Romano, Nunzio

2018-02-01

Indirect measurements of field-scale (hectometer grid-size) spatial-average near-surface soil moisture are becoming increasingly available by exploiting new-generation ground-based and satellite sensors. Nonetheless, modeling applications for water resources management require knowledge of plot-scale (1-5 m grid-size) soil moisture by using measurements through spatially-distributed sensor network systems. Since efforts to fulfill such requirements are not always possible due to time and budget constraints, alternative approaches are desirable. In this study, we explore the feasibility of determining spatial-average soil moisture and soil moisture patterns given the knowledge of long-term records of climate forcing data and topographic attributes. A downscaling approach is proposed that couples two different models: the Eco-Hydrological Bucket and Equilibrium Moisture from Topography. This approach helps identify the relative importance of two compound topographic indexes in explaining the spatial variation of soil moisture patterns, indicating valley- and hillslope-dependence controlled by lateral flow and radiative processes, respectively. The integrated model also detects temporal instability if the dominant type of topographic dependence changes with spatial-average soil moisture. Model application was carried out at three sites in different parts of Italy, each characterized by different environmental conditions. Prior calibration was performed by using sparse and sporadic soil moisture values measured by portable time domain reflectometry devices. Cross-site comparisons offer different interpretations in the explained spatial variation of soil moisture patterns, with time-invariant valley-dependence (site in northern Italy) and hillslope-dependence (site in southern Italy). The sources of soil moisture spatial variation at the site in central Italy are time-variant within the year and the seasonal change of topographic dependence can be conveniently correlated to a climate indicator such as the aridity index.

Ground-truthing electrical resistivity methods in support of submarine groundwater discharge studies: Examples from Hawaii, Washington, and California

USGS Publications Warehouse

Johnson, Cordell; Swarzenski, Peter W.; Richardson, Christina M.; Smith, Christopher G.; Kroeger, Kevin D.; Ganguli, Priya M.

2015-01-01

Rigorous ground-truthing at each field site showed that multi-channel electrcial resistivity techniques can reproduce the scales and dynamics of a seepage field when such data are correctly collected, and when the model inversions are tuned to field site characteristics. Such information can provide a unique perspective on the scales and dynamics of exchange processes within a coastal aquifer—information essential to scientists and resource managers alike.

Thresholds of understanding: Exploring assumptions of scale invariance vs. scale dependence in global biogeochemical models

NASA Astrophysics Data System (ADS)

Wieder, W. R.; Bradford, M.; Koven, C.; Talbot, J. M.; Wood, S.; Chadwick, O.

2016-12-01

High uncertainty and low confidence in terrestrial carbon (C) cycle projections reflect the incomplete understanding of how best to represent biologically-driven C cycle processes at global scales. Ecosystem theories, and consequently biogeochemical models, are based on the assumption that different belowground communities function similarly and interact with the abiotic environment in consistent ways. This assumption of "Scale Invariance" posits that environmental conditions will change the rate of ecosystem processes, but the biotic response will be consistent across sites. Indeed, cross-site comparisons and global-scale analyses suggest that climate strongly controls rates of litter mass loss and soil organic matter turnover. Alternatively, activities of belowground communities are shaped by particular local environmental conditions, such as climate and edaphic conditions. Under this assumption of "Scale Dependence", relationships generated by evolutionary trade-offs in acquiring resources and withstanding environmental stress dictate the activities of belowground communities and their functional response to environmental change. Similarly, local edaphic conditions (e.g. permafrost soils or reactive minerals that physicochemically stabilize soil organic matter on mineral surfaces) may strongly constrain the availability of substrates that biota decompose—altering the trajectory of soil biogeochemical response to perturbations. Identifying when scale invariant assumptions hold vs. where local variation in biotic communities or edaphic conditions must be considered is critical to advancing our understanding and representation of belowground processes in the face of environmental change. Here we introduce data sets that support assumptions of scale invariance and scale dependent processes and discuss their application in global-scale biogeochemical models. We identify particular domains over which assumptions of scale invariance may be appropriate and potential thresholds where shifts in ecosystem function may be expected. Finally, we discuss the mechanistic insight that can be applied in process-based models and datasets that can evaluate models across spatial and temporal scales.

The feasibility of using a universal Random Forest model to map tree height across different locations and vegetation types

NASA Astrophysics Data System (ADS)

Su, Y.; Guo, Q.; Jin, S.; Gao, S.; Hu, T.; Liu, J.; Xue, B. L.

2017-12-01

Tree height is an important forest structure parameter for understanding forest ecosystem and improving the accuracy of global carbon stock quantification. Light detection and ranging (LiDAR) can provide accurate tree height measurements, but its use in large-scale tree height mapping is limited by the spatial availability. Random Forest (RF) has been one of the most commonly used algorithms for mapping large-scale tree height through the fusion of LiDAR and other remotely sensed datasets. However, how the variances in vegetation types, geolocations and spatial scales of different study sites influence the RF results is still a question that needs to be addressed. In this study, we selected 16 study sites across four vegetation types in United States (U.S.) fully covered by airborne LiDAR data, and the area of each site was 100 km2. The LiDAR-derived canopy height models (CHMs) were used as the ground truth to train the RF algorithm to predict canopy height from other remotely sensed variables, such as Landsat TM imagery, terrain information and climate surfaces. To address the abovementioned question, 22 models were run under different combinations of vegetation types, geolocations and spatial scales. The results show that the RF model trained at one specific location or vegetation type cannot be used to predict tree height in other locations or vegetation types. However, by training the RF model using samples from all locations and vegetation types, a universal model can be achieved for predicting canopy height across different locations and vegetation types. Moreover, the number of training samples and the targeted spatial resolution of the canopy height product have noticeable influence on the RF prediction accuracy.

Critical scales to explain urban hydrological response: an application in Cranbrook, London

NASA Astrophysics Data System (ADS)

Cristiano, Elena; ten Veldhuis, Marie-Claire; Gaitan, Santiago; Ochoa Rodriguez, Susana; van de Giesen, Nick

2018-04-01

Rainfall variability in space and time, in relation to catchment characteristics and model complexity, plays an important role in explaining the sensitivity of hydrological response in urban areas. In this work we present a new approach to classify rainfall variability in space and time and we use this classification to investigate rainfall aggregation effects on urban hydrological response. Nine rainfall events, measured with a dual polarimetric X-Band radar instrument at the CAESAR site (Cabauw Experimental Site for Atmospheric Research, NL), were aggregated in time and space in order to obtain different resolution combinations. The aim of this work was to investigate the influence that rainfall and catchment scales have on hydrological response in urban areas. Three dimensionless scaling factors were introduced to investigate the interactions between rainfall and catchment scale and rainfall input resolution in relation to the performance of the model. Results showed that (1) rainfall classification based on cluster identification well represents the storm core, (2) aggregation effects are stronger for rainfall than flow, (3) model complexity does not have a strong influence compared to catchment and rainfall scales for this case study, and (4) scaling factors allow the adequate rainfall resolution to be selected to obtain a given level of accuracy in the calculation of hydrological response.

Crash Frequency Modeling Using Real-Time Environmental and Traffic Data and Unbalanced Panel Data Models

PubMed Central

Chen, Feng; Chen, Suren; Ma, Xiaoxiang

2016-01-01

Traffic and environmental conditions (e.g., weather conditions), which frequently change with time, have a significant impact on crash occurrence. Traditional crash frequency models with large temporal scales and aggregated variables are not sufficient to capture the time-varying nature of driving environmental factors, causing significant loss of critical information on crash frequency modeling. This paper aims at developing crash frequency models with refined temporal scales for complex driving environments, with such an effort providing more detailed and accurate crash risk information which can allow for more effective and proactive traffic management and law enforcement intervention. Zero-inflated, negative binomial (ZINB) models with site-specific random effects are developed with unbalanced panel data to analyze hourly crash frequency on highway segments. The real-time driving environment information, including traffic, weather and road surface condition data, sourced primarily from the Road Weather Information System, is incorporated into the models along with site-specific road characteristics. The estimation results of unbalanced panel data ZINB models suggest there are a number of factors influencing crash frequency, including time-varying factors (e.g., visibility and hourly traffic volume) and site-varying factors (e.g., speed limit). The study confirms the unique significance of the real-time weather, road surface condition and traffic data to crash frequency modeling. PMID:27322306

A comparison of single- and multi-site calibration and validation: a case study of SWAT in the Miyun Reservoir watershed, China

NASA Astrophysics Data System (ADS)

Bai, Jianwen; Shen, Zhenyao; Yan, Tiezhu

2017-09-01

An essential task in evaluating global water resource and pollution problems is to obtain the optimum set of parameters in hydrological models through calibration and validation. For a large-scale watershed, single-site calibration and validation may ignore spatial heterogeneity and may not meet the needs of the entire watershed. The goal of this study is to apply a multi-site calibration and validation of the Soil andWater Assessment Tool (SWAT), using the observed flow data at three monitoring sites within the Baihe watershed of the Miyun Reservoir watershed, China. Our results indicate that the multi-site calibration parameter values are more reasonable than those obtained from single-site calibrations. These results are mainly due to significant differences in the topographic factors over the large-scale area, human activities and climate variability. The multi-site method involves the division of the large watershed into smaller watersheds, and applying the calibrated parameters of the multi-site calibration to the entire watershed. It was anticipated that this case study could provide experience of multi-site calibration in a large-scale basin, and provide a good foundation for the simulation of other pollutants in followup work in the Miyun Reservoir watershed and other similar large areas.

Large-scale, high-performance and cloud-enabled multi-model analytics experiments in the context of the Earth System Grid Federation

NASA Astrophysics Data System (ADS)

Fiore, S.; Płóciennik, M.; Doutriaux, C.; Blanquer, I.; Barbera, R.; Williams, D. N.; Anantharaj, V. G.; Evans, B. J. K.; Salomoni, D.; Aloisio, G.

2017-12-01

The increased models resolution in the development of comprehensive Earth System Models is rapidly leading to very large climate simulations output that pose significant scientific data management challenges in terms of data sharing, processing, analysis, visualization, preservation, curation, and archiving.Large scale global experiments for Climate Model Intercomparison Projects (CMIP) have led to the development of the Earth System Grid Federation (ESGF), a federated data infrastructure which has been serving the CMIP5 experiment, providing access to 2PB of data for the IPCC Assessment Reports. In such a context, running a multi-model data analysis experiment is very challenging, as it requires the availability of a large amount of data related to multiple climate models simulations and scientific data management tools for large-scale data analytics. To address these challenges, a case study on climate models intercomparison data analysis has been defined and implemented in the context of the EU H2020 INDIGO-DataCloud project. The case study has been tested and validated on CMIP5 datasets, in the context of a large scale, international testbed involving several ESGF sites (LLNL, ORNL and CMCC), one orchestrator site (PSNC) and one more hosting INDIGO PaaS services (UPV). Additional ESGF sites, such as NCI (Australia) and a couple more in Europe, are also joining the testbed. The added value of the proposed solution is summarized in the following: it implements a server-side paradigm which limits data movement; it relies on a High-Performance Data Analytics (HPDA) stack to address performance; it exploits the INDIGO PaaS layer to support flexible, dynamic and automated deployment of software components; it provides user-friendly web access based on the INDIGO Future Gateway; and finally it integrates, complements and extends the support currently available through ESGF. Overall it provides a new "tool" for climate scientists to run multi-model experiments. At the time this contribution is being written, the proposed testbed represents the first implementation of a distributed large-scale, multi-model experiment in the ESGF/CMIP context, joining together server-side approaches for scientific data analysis, HPDA frameworks, end-to-end workflow management, and cloud computing.

Scale-dependent segregation of seeders and resprouters in cork oak (Quercus suber) forests.

PubMed

Coca, M; Pausas, J G

2012-02-01

Recent studies showed that disturbances and water availability determine the richness among plants with different post-fire strategies of Mediterranean-type ecosystems. The aim of this study was to determine whether or not the scale of analysis has an influence on the effects of these factors and, therefore, on the segregation of the dominant post-fire strategies, obligate seeders and obligate resprouters, and facultative species. We recorded all woody species and geographical features on 94 (75 m(2)) plots of cork oak woodlands in the southern Iberian Peninsula. For each regenerative type (resprouters, seeders and species with both traits--facultative species), we tested the relationship between the number of species and the predictors using a generalised linear mixed model. The fixed predictor considered at the large scale was altitude, and fixed predictors considered at the local scale were aspect (north/south) and disturbance (fire and clearing by heavy machinery; yes/no). The random predictor was the factor of site. When this factor did not have significant effect for some regenerative types, these relationships was tested using a generalised linear model. Resprouting species were most represented at lower altitudes and in undisturbed sites, while seeders were also at lower altitudes but mostly on south-facing slopes, especially south-facing disturbed sites. For facultative species, site is the most important variable. The proportion of seeders from the total species is not related to altitude, but it is related to disturbance and aspect. These results suggest that there is no segregation of the richness of seeders and resprouters at the large scale (altitudinal gradient). Differences appeared at the local scale (aspect and disturbance).

Compulsive use of social networking sites in Belgium: prevalence, profile, and the role of attitude toward work and school.

PubMed

De Cock, Rozane; Vangeel, Jolien; Klein, Annabelle; Minotte, Pascal; Rosas, Omar; Meerkerk, Gert-Jan

2014-03-01

A representative sample (n=1,000) of the Belgian population aged 18 years and older filled out an online questionnaire on their Internet use in general and their use of social networking sites (SNS) in particular. We measured total time spent on the Internet, time spent on SNS, number of SNS profiles, gender, age, schooling level, income, job occupation, and leisure activities, and we integrated several psychological scales such as the Quick Big Five and the Mastery Scale. Hierarchical multiple regression modeling shows that gender and age explain an important part of the compulsive SNS score (5%) as well as psychological scales (20%), but attitude toward school (additional 3%) and income (2.5%) also add to explained variance in predictive models of compulsive SNS use.

Differentiating Impacts of Watershed Development from Superfund Sites on Stream Macroinvertebrates

EPA Science Inventory

Urbanization effect models were developed and verified at whole watershed scales to predict and differentiate between effects on aquatic life from diffuse, non-point source (NPS) urbanization in the watershed and effects of known local, site-specific origin point sources, contami...

The Relative Importance of the Vadose Zone in Multimedia Risk Assessment Modeling Applied at a National Scale: An Analysis of Benzene Using 3MRA

NASA Astrophysics Data System (ADS)

Babendreier, J. E.

2002-05-01

Evaluating uncertainty and parameter sensitivity in environmental models can be a difficult task, even for low-order, single-media constructs driven by a unique set of site-specific data. The challenge of examining ever more complex, integrated, higher-order models is a formidable one, particularly in regulatory settings applied on a national scale. Quantitative assessment of uncertainty and sensitivity within integrated, multimedia models that simulate hundreds of sites, spanning multiple geographical and ecological regions, will ultimately require a systematic, comparative approach coupled with sufficient computational power. The Multimedia, Multipathway, and Multireceptor Risk Assessment Model (3MRA) is an important code being developed by the United States Environmental Protection Agency for use in site-scale risk assessment (e.g. hazardous waste management facilities). The model currently entails over 700 variables, 185 of which are explicitly stochastic. The 3MRA can start with a chemical concentration in a waste management unit (WMU). It estimates the release and transport of the chemical throughout the environment, and predicts associated exposure and risk. The 3MRA simulates multimedia (air, water, soil, sediments), pollutant fate and transport, multipathway exposure routes (food ingestion, water ingestion, soil ingestion, air inhalation, etc.), multireceptor exposures (resident, gardener, farmer, fisher, ecological habitats and populations), and resulting risk (human cancer and non-cancer effects, ecological population and community effects). The 3MRA collates the output for an overall national risk assessment, offering a probabilistic strategy as a basis for regulatory decisions. To facilitate model execution of 3MRA for purposes of conducting uncertainty and sensitivity analysis, a PC-based supercomputer cluster was constructed. Design of SuperMUSE, a 125 GHz Windows-based Supercomputer for Model Uncertainty and Sensitivity Evaluation is described, along with the conceptual layout of an accompanying java-based paralleling software toolset. Preliminary work is also reported for a scenario involving Benzene disposal that describes the relative importance of the vadose zone in driving risk levels for ecological receptors and human health. Incorporating landfills, waste piles, aerated tanks, surface impoundments, and land application units, the site-based data used in the analysis included 201 national facilities representing 419 site-WMU combinations.

Dynamic occupancy models for explicit colonization processes

USGS Publications Warehouse

Broms, Kristin M.; Hooten, Mevin B.; Johnson, Devin S.; Altwegg, Res; Conquest, Loveday

2016-01-01

The dynamic, multi-season occupancy model framework has become a popular tool for modeling open populations with occupancies that change over time through local colonizations and extinctions. However, few versions of the model relate these probabilities to the occupancies of neighboring sites or patches. We present a modeling framework that incorporates this information and is capable of describing a wide variety of spatiotemporal colonization and extinction processes. A key feature of the model is that it is based on a simple set of small-scale rules describing how the process evolves. The result is a dynamic process that can account for complicated large-scale features. In our model, a site is more likely to be colonized if more of its neighbors were previously occupied and if it provides more appealing environmental characteristics than its neighboring sites. Additionally, a site without occupied neighbors may also become colonized through the inclusion of a long-distance dispersal process. Although similar model specifications have been developed for epidemiological applications, ours formally accounts for detectability using the well-known occupancy modeling framework. After demonstrating the viability and potential of this new form of dynamic occupancy model in a simulation study, we use it to obtain inference for the ongoing Common Myna (Acridotheres tristis) invasion in South Africa. Our results suggest that the Common Myna continues to enlarge its distribution and its spread via short distance movement, rather than long-distance dispersal. Overall, this new modeling framework provides a powerful tool for managers examining the drivers of colonization including short- vs. long-distance dispersal, habitat quality, and distance from source populations.

Upscaling Empirically Based Conceptualisations to Model Tropical Dominant Hydrological Processes for Historical Land Use Change

NASA Astrophysics Data System (ADS)

Toohey, R.; Boll, J.; Brooks, E.; Jones, J.

2009-12-01

Surface runoff and percolation to ground water are two hydrological processes of concern to the Atlantic slope of Costa Rica because of their impacts on flooding and drinking water contamination. As per legislation, the Costa Rican Government funds land use management from the farm to the regional scale to improve or conserve hydrological ecosystem services. In this study, we examined how land use (e.g., forest, coffee, sugar cane, and pasture) affects hydrological response at the point, plot (1 m2), and the field scale (1-6ha) to empirically conceptualize the dominant hydrological processes in each land use. Using our field data, we upscaled these conceptual processes into a physically-based distributed hydrological model at the field, watershed (130 km2), and regional (1500 km2) scales. At the point and plot scales, the presence of macropores and large roots promoted greater vertical percolation and subsurface connectivity in the forest and coffee field sites. The lack of macropores and large roots, plus the addition of management artifacts (e.g., surface compaction and a plough layer), altered the dominant hydrological processes by increasing lateral flow and surface runoff in the pasture and sugar cane field sites. Macropores and topography were major influences on runoff generation at the field scale. Also at the field scale, antecedent moisture conditions suggest a threshold behavior as a temporal control on surface runoff generation. However, in this tropical climate with very intense rainstorms, annual surface runoff was less than 10% of annual precipitation at the field scale. Significant differences in soil and hydrological characteristics observed at the point and plot scales appear to have less significance when upscaled to the field scale. At the point and plot scales, percolation acted as the dominant hydrological process in this tropical environment. However, at the field scale for sugar cane and pasture sites, saturation-excess runoff increased as irrigation intensity and duration (e.g., quantity) increased. Upscaling our conceptual models to the watershed and regional scales, historical data (1970-2004) was used to investigate whether dominant hydrological processes changed over time due to land use change. Preliminary investigations reveal much higher runoff coefficients (<30%) at the larger watershed scales. The increase in importance of runoff at the larger geographic scales suggests an emerging process and process non-linearity between the smaller and larger scales. Upscaling is an important and useful concept when investigating catchment response using the tools of field work and/or physically distributed hydrological modeling.

Match and mismatch - comparing plant phenological metrics from ground-observations and from a prognostic model

NASA Astrophysics Data System (ADS)

Rutishauser, This; Stöckli, Reto; Jeanneret, François; Peñuelas, Josep

2010-05-01

Changes in the seasonality of life cycles of plants as recorded in phenological observations have been widely analysed at the species level with data available for many decades back in time. At the same time, seasonality changes in satellite-based observations and prognostic phenology models comprise information at the pixel-size or landscape scale. Change analysis of satellite-based records is restricted due to relatively short satellite records that further include gaps while model-based analyses are biased due to current model deficiencies., At 30 selected sites across Europe, we analysed three different sources of plant seasonality during the 1971-2000 period. Data consisted of (1) species-specific development stages of flowering and leave-out with different species observed at each site. (2) We used a synthetic phenological metric that integrates the common interannual phenological signal across all species at one site. (3) We estimated daily Leaf Area Index with a prognostic phenology model. The prior uncertainties of the model's empirical parameter space are constrained by assimilating the Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) and Leaf Area Index (LAI) from the MODerate Resolution Imaging Spectroradiometer (MODIS). We extracted the day of year when the 25%, 50% and 75% thresholds were passed each spring. The question arises how the three phenological signals compare and correlate across climate zones in Europe. Is there a match between single species observations, species-based ground-observed metrics and the landscape-scale prognostic model? Are there single key-species across Europe that best represent a landscape scale measure from the prognostic model? Can one source substitute another and serve as proxy-data? What can we learn from potential mismatches? Focusing on changes in spring this contribution presents first results of an ongoing comparison study from a number of European test sites that will be extended to the pan-European phenological database Cost725 and PEP725.

Vadose Zone Transport Field Study: Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Andy L.; Conrad, Mark E.; Daily, William D.

2006-07-31

From FY 2000 through FY 2003, a series of vadose zone transport field experiments were conducted as part of the U.S. Department of Energy’s Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, and managed by the Pacific Northwest National Laboratory (PNNL). The series of experiments included two major field campaigns, one at a 299-E24-11 injection test site near PUREX and a second at a clastic dike site off Army Loop Road. The goals of these experiments were to improve our understanding of vadose zone transport processes; to develop data sets tomore » validate and calibrate vadose zone flow and transport models; and to identify advanced monitoring techniques useful for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanford’s vadose zone. Results of these tests have led to a better understanding of the vadose zone. Fine-scale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy. Conceptual models have been updated to include lateral spreading and numerical models of unsaturated flow and transport have revised accordingly. A new robust model based on the concept of a connectivity tensor was developed to describe saturation-dependent anisotropy in strongly heterogeneous soils and has been incorporated into PNNL’s Subsurface Transport Over Multiple Phases (STOMP) simulator. Application to field-scale transport problems have led to a better understanding plume behavior at a number of sites where lateral spreading may have dominated waste migration (e.g. BC Cribs and Trenches). The improved models have been also coupled with inverse models and newly-developed parameter scaling techniques to allow estimation of field-scale and effective transport parameters for the vadose zone. The development and utility of pedotransfer functions for describing fine-scale hydrogeochemical heterogeneity and for incorporating this heterogeneity into reactive transport models was explored. An approach based on grain-size statistics appears feasible and has been used to describe heterogeneity in hydraulic properties and sorption properties, such as the cation exchange capacity and the specific surface area of Hanford sediments. This work has also led to the development of inverse modeling capabilities for time-dependent, subsurface, reactive transport with transient flow fields using an automated optimization algorithm. In addition, a number of geophysical techniques investigated for their potential to provide detailed information on the subtle changes in lithology and bedding surfaces; plume delineation, leak detection. High-resolution resistivity is now being used for detecting saline plumes at several waste sites at Hanford, including tank farms. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports, in addition to numerous technical notes and peer reviewed papers.« less

An integrated assessment of location-dependent scaling for microalgae biofuel production facilities

DOE PAGES

Coleman, André M.; Abodeely, Jared M.; Skaggs, Richard L.; ...

2014-06-19

Successful development of a large-scale microalgae-based biofuels industry requires comprehensive analysis and understanding of the feedstock supply chain—from facility siting and design through processing and upgrading of the feedstock to a fuel product. The evolution from pilot-scale production facilities to energy-scale operations presents many multi-disciplinary challenges, including a sustainable supply of water and nutrients, operational and infrastructure logistics, and economic competitiveness with petroleum-based fuels. These challenges are partially addressed by applying the Integrated Assessment Framework (IAF) – an integrated multi-scale modeling, analysis, and data management suite – to address key issues in developing and operating an open-pond microalgae production facility.more » This is done by analyzing how variability and uncertainty over space and through time affect feedstock production rates, and determining the site-specific “optimum” facility scale to minimize capital and operational expenses. This approach explicitly and systematically assesses the interdependence of biofuel production potential, associated resource requirements, and production system design trade-offs. To provide a baseline analysis, the IAF was applied in this paper to a set of sites in the southeastern U.S. with the potential to cumulatively produce 5 billion gallons per year. Finally, the results indicate costs can be reduced by scaling downstream processing capabilities to fit site-specific growing conditions, available and economically viable resources, and specific microalgal strains.« less

On the design of paleoenvironmental data networks for estimating large-scale patterns of climate

NASA Astrophysics Data System (ADS)

Kutzbach, J. E.; Guetter, P. J.

1980-09-01

Guidelines are determined for the spatial density and location of climatic variables (temperature and precipitation) that are appropriate for estimating the continental- to hemispheric-scale pattern of atmospheric circulation (sea-level pressure). Because instrumental records of temperature and precipitation simulate the climatic information that is contained in certain paleoenvironmental records (tree-ring, pollen, and written-documentary records, for example), these guidelines provide useful sampling strategies for reconstructing the pattern of atmospheric circulation from paleoenvironmental records. The statistical analysis uses a multiple linear regression model. The sampling strategies consist of changes in site density (from 0.5 to 2.5 sites per million square kilometers) and site location (from western North American sites only to sites in Japan, North America, and western Europe) of the climatic data. The results showed that the accuracy of specification of the pattern of sea-level pressure: (1) is improved if sites with climatic records are spread as uniformly as possible over the area of interest; (2) increases with increasing site density-at least up to the maximum site density used in this study; (3) is improved if sites cover an area that extends considerably beyond the limits of the area of interest. The accuracy of specification was lower for independent data than for the data that were used to develop the regression model; some skill was found for almost all sampling strategies.

The Temporal Dynamics of Spatial Patterns of Observed Soil Moisture Interpreted Using the Hydrus 1-D Model

NASA Astrophysics Data System (ADS)

Chen, M.; Willgoose, G. R.; Saco, P. M.

2009-12-01

This paper investigates the soil moisture dynamics over two subcatchments (Stanley and Krui) in the Goulburn River in NSW during a three year period (2005-2007) using the Hydrus 1-D unsaturated soil water flow model. The model was calibrated to the seven Stanley microcatchment sites (1 sqkm site) using continuous time surface 30cm and full profile soil moisture measurements. Soil type, leaf area index and soil depth were found to be the key parameters changing model fit to the soil moisture time series. They either shifted the time series up or down, changed the steepness of dry-down recessions or determined the lowest point of soil moisture dry-down respectively. Good correlations were obtained between observed and simulated soil water storage (R=0.8-0.9) when calibrated parameters for one site were applied to the other sites. Soil type was also found to be the main determinant (after rainfall) of the mean of modelled soil moisture time series. Simulations of top 30cm were better than those of the whole soil profile. Within the Stanley microcatchment excellent soil moisture matches could be generated simply by adjusting the mean of soil moisture up or down slightly. Only minor modification of soil properties from site to site enable good fits for all of the Stanley sites. We extended the predictions of soil moisture to a larger spatial scale of the Krui catchment (sites up to 30km distant from Stanley) using soil and vegetation parameters from Stanley but the locally recorded rainfall at the soil moisture measurement site. The results were encouraging (R=0.7~0.8). These results show that it is possible to use a calibrated soil moisture model to extrapolate the soil moisture to other sites for a catchment with an area of up to 1000km2. This paper demonstrates the potential usefulness of continuous time, point scale soil moisture (typical of that measured by permanently installed TDR probes) in predicting the soil wetness status over a catchment of significant size.

Modeling CO2 Storage in Fractured Reservoirs: Fracture-Matrix Interactions of Free-Phase and Dissolved CO2

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Zhou, Q.; Birkholzer, J. T.

2017-12-01

The injection of supercritical CO2 (scCO2) in fractured reservoirs has been conducted at several storage sites. However, no site-specific dual-continuum modeling for fractured reservoirs has been reported and modeling studies have generally underestimated the fracture-matrix interactions. We developed a conceptual model for enhanced CO2 storage to take into account global scCO2 migration in the fracture continuum, local storage of scCO2 and dissolved CO2 (dsCO2) in the matrix continuum, and driving forces for scCO2 invasion and dsCO2 diffusion from fractures. High-resolution discrete fracture-matrix models were developed for a column of idealized matrix blocks bounded by vertical and horizontal fractures and for a km-scale fractured reservoir. The column-scale simulation results show that equilibrium storage efficiency strongly depends on matrix entry capillary pressure and matrix-matrix connectivity while the time scale to reach equilibrium is sensitive to fracture spacing and matrix flow properties. The reservoir-scale modeling results shows that the preferential migration of scCO2 through fractures is coupled with bulk storage in the rock matrix that in turn retards the fracture scCO2 plume. We also developed unified-form diffusive flux equations to account for dsCO2 storage in brine-filled matrix blocks and found solubility trapping is significant in fractured reservoirs with low-permeability matrix.

Yield and Depth of Burial Hydrodynamic Calculations in Granodiorite: Implications for the North Korean Test Site

DTIC Science & Technology

2011-09-01

the existence of a test site body wave magnitude (mb) bias between U. S. and the former Soviet Union test sites in Nevada and Semipalatinsk . The use...YIELD AND DEPTH OF BURIAL HYDRODYNAMIC CALCULATIONS IN GRANODIORITE:IMPLICATIONS FOR THE NORTH KOREAN TEST SITE Esteban Rougier, Christopher R...Korean test site and the May 2009 test . When compared to the Denny and Johnson (1991) and to the Heard and Ackerman (1967) cavity radius scaling models

The Site-Scale Saturated Zone Flow Model for Yucca Mountain

NASA Astrophysics Data System (ADS)

Al-Aziz, E.; James, S. C.; Arnold, B. W.; Zyvoloski, G. A.

2006-12-01

This presentation provides a reinterpreted conceptual model of the Yucca Mountain site-scale flow system subject to all quality assurance procedures. The results are based on a numerical model of site-scale saturated zone beneath Yucca Mountain, which is used for performance assessment predictions of radionuclide transport and to guide future data collection and modeling activities. This effort started from the ground up with a revised and updated hydrogeologic framework model, which incorporates the latest lithology data, and increased grid resolution that better resolves the hydrogeologic framework, which was updated throughout the model domain. In addition, faults are much better represented using the 250× 250- m2 spacing (compared to the previous model's 500× 500-m2 spacing). Data collected since the previous model calibration effort have been included and they comprise all Nye County water-level data through Phase IV of their Early Warning Drilling Program. Target boundary fluxes are derived from the newest (2004) Death Valley Regional Flow System model from the US Geologic Survey. A consistent weighting scheme assigns importance to each measured water-level datum and boundary flux extracted from the regional model. The numerical model is calibrated by matching these weighted water level measurements and boundary fluxes using parameter estimation techniques, along with more informal comparisons of the model to hydrologic and geochemical information. The model software (hydrologic simulation code FEHM~v2.24 and parameter estimation software PEST~v5.5) and model setup facilitates efficient calibration of multiple conceptual models. Analyses evaluate the impact of these updates and additional data on the modeled potentiometric surface and the flowpaths emanating from below the repository. After examining the heads and permeabilities obtained from the calibrated models, we present particle pathways from the proposed repository and compare them to those from the previous model calibration. Specific discharge at a point 5~km from the repository is also examined and found to be within acceptable uncertainty. The results show that updated model yields a calibration with smaller residuals than the previous model revision while ensuring that flowpaths follow measured gradients and paths derived from hydrochemical analyses. This work was supported by the Yucca Mountain Site Characterization Office as part of the Civilian Radioactive Waste Management Program, which is managed by the U.S. Department of Energy, Yucca Mountain Site Characterization Project. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE AC04 94AL85000.

Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

USGS Publications Warehouse

Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Campbell, Kenneth; Abrahamson, Norman; Silva, Walter

2012-01-01

Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.

A hierarchical Bayesian GEV model for improving local and regional flood quantile estimates

NASA Astrophysics Data System (ADS)

Lima, Carlos H. R.; Lall, Upmanu; Troy, Tara; Devineni, Naresh

2016-10-01

We estimate local and regional Generalized Extreme Value (GEV) distribution parameters for flood frequency analysis in a multilevel, hierarchical Bayesian framework, to explicitly model and reduce uncertainties. As prior information for the model, we assume that the GEV location and scale parameters for each site come from independent log-normal distributions, whose mean parameter scales with the drainage area. From empirical and theoretical arguments, the shape parameter for each site is shrunk towards a common mean. Non-informative prior distributions are assumed for the hyperparameters and the MCMC method is used to sample from the joint posterior distribution. The model is tested using annual maximum series from 20 streamflow gauges located in an 83,000 km2 flood prone basin in Southeast Brazil. The results show a significant reduction of uncertainty estimates of flood quantile estimates over the traditional GEV model, particularly for sites with shorter records. For return periods within the range of the data (around 50 years), the Bayesian credible intervals for the flood quantiles tend to be narrower than the classical confidence limits based on the delta method. As the return period increases beyond the range of the data, the confidence limits from the delta method become unreliable and the Bayesian credible intervals provide a way to estimate satisfactory confidence bands for the flood quantiles considering parameter uncertainties and regional information. In order to evaluate the applicability of the proposed hierarchical Bayesian model for regional flood frequency analysis, we estimate flood quantiles for three randomly chosen out-of-sample sites and compare with classical estimates using the index flood method. The posterior distributions of the scaling law coefficients are used to define the predictive distributions of the GEV location and scale parameters for the out-of-sample sites given only their drainage areas and the posterior distribution of the average shape parameter is taken as the regional predictive distribution for this parameter. While the index flood method does not provide a straightforward way to consider the uncertainties in the index flood and in the regional parameters, the results obtained here show that the proposed Bayesian method is able to produce adequate credible intervals for flood quantiles that are in accordance with empirical estimates.

Atomic-scale distortion of optically activated Sm dopants identified with site-selective X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Ishii, Masashi; Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce; Hu, Yongfeng; Sham, Tsun-Kong; Harako, Susumu; Zhao, Xin-Wei; Komuro, Shuji

2013-10-01

The local structure of luminescent Sm dopants was investigated using an X-ray absorption fine-structure technique with X-ray-excited optical luminescence. Because this technique evaluates X-ray absorption from luminescence, only optically active sites are analyzed. The Sm L3 near-edge spectrum contains split 5d states and a shake-up transition that are specific to luminescent Sm. Theoretical calculations using cluster models identified an atomic-scale distortion that can reproduce the split 5d states. The model with C4v local symmetry and compressive bond length of Sm-O of a six-fold oxygen (SmO6) cluster is most consistent with the experimental results.

Upscaling of soil moisture measurements in NW Italy

NASA Astrophysics Data System (ADS)

Ferraris, Stefano; Canone, Davide; Previati, Maurizio; Brunod, Christian; Ratto, Sara; Cauduro, Marco

2015-04-01

There is large mismatch in spatial scale between the climate and meteorological model grid, and the scale of soil and vegetation measurements. Remote sensing data can help to fit the model scale, but they cannot provide rootzone data. In this work some soil moisture datasets are analysed for the sake of providing larger scale estimation of soil moisture and water and energy fluxes. The first dataset refers to a plain site near Torino, where measurements are taken since 1997 (Baudena et al., 2012), and a mountain site close to the town. The second one is a dataset in the mountains of Valle d'Aosta (Brocca et al., 2013), where 4 years of data are available. The use of digital elevation models and vegetation maps is shown in this work. Some soil processes (e.g. Whalley et al., 2012) are usually disregarded, but in this work their possible impact is considered. References L. Brocca, A. Tarpanelli, T. Moramarco, F. Melone, S.M. Ratto, M. Cauduro, S. Ferraris, N. Berni, F. Ponziani, W. Wagner, T. Melzer (2013). Soil Moisture Estimation in Alpine Catchments through Modeling and Satellite Observations VADOSE ZONE JOURNAL, vol. 8-2, p. 1-10, doi:10.2136/vzj2012.0102 M. Baudena, I. Bevilacqua, D. Canone, S. Ferraris, M. Previati, A. Provenzale (2012). Soil water dynamics at a midlatitude test site: Field measurements and box modeling approaches. JOURNAL OF HYDROLOGY, vol. 414-415, p. 329-340, ISSN: 0022-1694, doi: 10.1016/j.jhydrol.2011.11.009 W.R. Whalley, G.P. Matthews, S. Ferraris (2012). The effect of compaction and shear deformation of saturated soil on hydraulic conductivity. SOIL & TILLAGE RESEARCH, vol. 125, p. 23-29, ISSN: 0167-1987

Genome-scale dynamic modeling of the competition between Rhodoferax and Geobacter in anoxic subsurface environments

PubMed Central

Zhuang, Kai; Izallalen, Mounir; Mouser, Paula; Richter, Hanno; Risso, Carla; Mahadevan, Radhakrishnan; Lovley, Derek R

2011-01-01

The advent of rapid complete genome sequencing, and the potential to capture this information in genome-scale metabolic models, provide the possibility of comprehensively modeling microbial community interactions. For example, Rhodoferax and Geobacter species are acetate-oxidizing Fe(III)-reducers that compete in anoxic subsurface environments and this competition may have an influence on the in situ bioremediation of uranium-contaminated groundwater. Therefore, genome-scale models of Geobacter sulfurreducens and Rhodoferax ferrireducens were used to evaluate how Geobacter and Rhodoferax species might compete under diverse conditions found in a uranium-contaminated aquifer in Rifle, CO. The model predicted that at the low rates of acetate flux expected under natural conditions at the site, Rhodoferax will outcompete Geobacter as long as sufficient ammonium is available. The model also predicted that when high concentrations of acetate are added during in situ bioremediation, Geobacter species would predominate, consistent with field-scale observations. This can be attributed to the higher expected growth yields of Rhodoferax and the ability of Geobacter to fix nitrogen. The modeling predicted relative proportions of Geobacter and Rhodoferax in geochemically distinct zones of the Rifle site that were comparable to those that were previously documented with molecular techniques. The model also predicted that under nitrogen fixation, higher carbon and electron fluxes would be diverted toward respiration rather than biomass formation in Geobacter, providing a potential explanation for enhanced in situ U(VI) reduction in low-ammonium zones. These results show that genome-scale modeling can be a useful tool for predicting microbial interactions in subsurface environments and shows promise for designing bioremediation strategies. PMID:20668487

Evaluation of physical activity web sites for use of behavior change theories.

PubMed

Doshi, Amol; Patrick, Kevin; Sallis, James F; Calfas, Karen

2003-01-01

Physical activity (PA) Web sites were assessed for their use of behavior change theories, including constructs of the health belief model, Transtheoretical Model, social cognitive theory, and the theory of reasoned action and planned behavior. An evaluation template for assessing PA Web sites was developed, and content validity and interrater reliability were demonstrated. Two independent raters evaluated 24 PA Web sites. Web sites varied widely in application of theory-based constructs, ranging from 5 to 48 on a 100-point scale. The most common intervention strategies were general information, social support, and realistic goal areas. Coverage of theory-based strategies was low, varying from 26% for social cognitive theory to 39% for health belief model. Overall, PA Web sites provided little assessment, feedback, or individually tailored assistance for users. They were unable to substantially tailor the on-line experience for users at different stages of change or different demographic characteristics.

Spatial Scaling of Environmental Variables Improves Species-Habitat Models of Fishes in a Small, Sand-Bed Lowland River

PubMed Central

Radinger, Johannes; Wolter, Christian; Kail, Jochem

2015-01-01

Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological and in-stream habitat variables and their spatial scales of influence is poorly understood. Applying boosted regression trees, we developed species-habitat models for 13 fish species in a sand-bed lowland river based on river morphological and in-stream habitat data. First, we calculated mean values for the predictor variables in five distance classes (from the sampling site up to 4000 m up- and downstream) to identify the spatial scale that best predicts the presence of fish species. Second, we compared the suitability of measured variables and assessment scores related to natural reference conditions. Third, we identified variables which best explained the presence of fish species. The mean model quality (AUC = 0.78, area under the receiver operating characteristic curve) significantly increased when information on the habitat conditions up- and downstream of a sampling site (maximum AUC at 2500 m distance class, +0.049) and topological variables (e.g., stream order) were included (AUC = +0.014). Both measured and assessed variables were similarly well suited to predict species’ presence. Stream order variables and measured cross section features (e.g., width, depth, velocity) were best-suited predictors. In addition, measured channel-bed characteristics (e.g., substrate types) and assessed longitudinal channel features (e.g., naturalness of river planform) were also good predictors. These findings demonstrate (i) the applicability of high resolution river morphological and instream-habitat data (measured and assessed variables) to predict fish presence, (ii) the importance of considering habitat at spatial scales larger than the sampling site, and (iii) that the importance of (river morphological) habitat characteristics differs depending on the spatial scale. PMID:26569119

Developing and Testing a Robust, Multi-Scale Framework for the Recovery of Longleaf Pine Understory Communities

DTIC Science & Technology

2015-05-01

Model averaging for species richness on post-agricultural sites (1000 m2) with a landscape radius of 150 m. Table 3.4.8. Model selection for species ... richness on post-agricultural sites (1000 m2) with a landscape radius of 150 m. Table 3.4.9. Model averaging for proportion of reference species on...Direct, indirect, and total standardized effects on species richness . Table 4.1.1. Species and number of seeds added to the experimental plots at

Prediction of Continental-Scale Net Ecosystem Carbon Exchange by Combining MODIS and AmeriFlux Data

NASA Astrophysics Data System (ADS)

Xiao, J.; Zhuang, Q.

2007-12-01

There is growing interest in scaling up net ecosystem exchange (NEE) measured at eddy covariance flux towers to regional scales. Here we used remote sensing data from the MODIS instrument on board NASA's Terra satellite to extrapolate NEE measured at AmeriFlux sites to the continental scale. We combined MODIS data and NEE measurements from a number of AmeriFlux sites with a variety of vegetation types (e.g., forests, grasslands, shrublands, savannas, and croplands) to develop a predictive NEE model using a regression tree approach. The model was trained using 2000-2003 NEE measurements, and the performance of the model was evaluated using independent data over the period 2004-2006. We found that the model predicted NEE with reasonable accuracy at the continental scale. The R-squared values are 0.50 for all vegetation types combined and 0.72 for deciduous forests. We then applied the model to the conterminous U.S. and predicted NEE for each 500m by 500m cell over the period 2001-2006. Based on the wall-to-wall NEE estimates, we examined the spatial and temporal distributions of annual NEE and interannual variability of annual NEE across the conterminous U.S. over the study period (2001-2006). Our scaling-up approach implicitly considered the effects of climate variability, land use/land cover change, disturbances, extreme climate events, and management practices, and thus our annual NEE estimates represents the net carbon fluxes between the terrestrial biosphere and the atmosphere in the conterminous U.S.

Developing a regional scale approach for modelling the impacts of fertiliser regime on N2O emissions in Ireland

NASA Astrophysics Data System (ADS)

Zimmermann, Jesko; Jones, Michael

2016-04-01

Agriculture can be significant contributor to greenhouse gas emissions, this is especially prevalent in Ireland where the agricultural sector accounts for a third of total emissions. The high emissions are linked to both the importance of agriculture in the Irish economy and the focus on dairy and beef production. In order to reduce emissions three main categories are explored: (1) reduction of methane emissions from cattle, (2) reduction of nitrous oxide emissions from fertilisation, and (3) fostering the carbon sequestration potential of soils. The presented research focuses on the latter two categories, especially changes in fertiliser amount and composition. Soil properties and climate conditions measured at the four experimental sites (two silage and two spring barley) were used to parameterise four biogeochemical models (DayCent, ECOSSE, DNDC 9.4, and DNDC 9.5). All sites had a range of different fertiliser regimes applied. This included changes in amount (0 to 500 kg N/ha on grassland and 0 to 200 kg N/ha on arable fields), fertiliser type (calcium ammonium nitrate and urea), and added inhibitors (the nitrification inhibitor DCD, and the urease inhibitor Agrotain). Overall, 20 different treatments were applied to the grassland sites, and 17 to the arable sites. Nitrous oxide emissions, measured in 2013 and 2014 at all sites using closed chambers, were made available to validate model results for these emissions. To assess model performance for the daily measurements, the Root Mean Square Error (RMSE) was compared to the measured 95% confidence interval of the measured data (RMSE95). Bias was tested comparing the relative error (RE) the 95 % confidence interval of the relative error (RE95). Preliminary results show mixed model performance, depending on the model, site, and the fertiliser regime. However, with the exception of urea fertilisation and added inhibitors, all scenarios were reproduced by at least one model with no statistically significant total error (RMSE < RMSE95) or bias (RE< RE95). A general trend observed was that model performance declined with increased fertilisation rates. Overall, DayCent showed the best performance, however it does not provide the possibility to model the addition urease inhibitors. The results suggest that modelling changes in fertiliser regime on a large scale may require a multi-model approach to assure best performance. Ultimately, the research aims to develop a GIS based platform to apply such an approach on a regional scale.

Fine-Scale Exposure to Allergenic Pollen in the Urban Environment: Evaluation of Land Use Regression Approach.

PubMed

Hjort, Jan; Hugg, Timo T; Antikainen, Harri; Rusanen, Jarmo; Sofiev, Mikhail; Kukkonen, Jaakko; Jaakkola, Maritta S; Jaakkola, Jouni J K

2016-05-01

Despite the recent developments in physically and chemically based analysis of atmospheric particles, no models exist for resolving the spatial variability of pollen concentration at urban scale. We developed a land use regression (LUR) approach for predicting spatial fine-scale allergenic pollen concentrations in the Helsinki metropolitan area, Finland, and evaluated the performance of the models against available empirical data. We used grass pollen data monitored at 16 sites in an urban area during the peak pollen season and geospatial environmental data. The main statistical method was generalized linear model (GLM). GLM-based LURs explained 79% of the spatial variation in the grass pollen data based on all samples, and 47% of the variation when samples from two sites with very high concentrations were excluded. In model evaluation, prediction errors ranged from 6% to 26% of the observed range of grass pollen concentrations. Our findings support the use of geospatial data-based statistical models to predict the spatial variation of allergenic grass pollen concentrations at intra-urban scales. A remote sensing-based vegetation index was the strongest predictor of pollen concentrations for exposure assessments at local scales. The LUR approach provides new opportunities to estimate the relations between environmental determinants and allergenic pollen concentration in human-modified environments at fine spatial scales. This approach could potentially be applied to estimate retrospectively pollen concentrations to be used for long-term exposure assessments. Hjort J, Hugg TT, Antikainen H, Rusanen J, Sofiev M, Kukkonen J, Jaakkola MS, Jaakkola JJ. 2016. Fine-scale exposure to allergenic pollen in the urban environment: evaluation of land use regression approach. Environ Health Perspect 124:619-626; http://dx.doi.org/10.1289/ehp.1509761.

Occupancy estimation and the closure assumption

USGS Publications Warehouse

Rota, Christopher T.; Fletcher, Robert J.; Dorazio, Robert M.; Betts, Matthew G.

2009-01-01

1. Recent advances in occupancy estimation that adjust for imperfect detection have provided substantial improvements over traditional approaches and are receiving considerable use in applied ecology. To estimate and adjust for detectability, occupancy modelling requires multiple surveys at a site and requires the assumption of 'closure' between surveys, i.e. no changes in occupancy between surveys. Violations of this assumption could bias parameter estimates; however, little work has assessed model sensitivity to violations of this assumption or how commonly such violations occur in nature. 2. We apply a modelling procedure that can test for closure to two avian point-count data sets in Montana and New Hampshire, USA, that exemplify time-scales at which closure is often assumed. These data sets illustrate different sampling designs that allow testing for closure but are currently rarely employed in field investigations. Using a simulation study, we then evaluate the sensitivity of parameter estimates to changes in site occupancy and evaluate a power analysis developed for sampling designs that is aimed at limiting the likelihood of closure. 3. Application of our approach to point-count data indicates that habitats may frequently be open to changes in site occupancy at time-scales typical of many occupancy investigations, with 71% and 100% of species investigated in Montana and New Hampshire respectively, showing violation of closure across time periods of 3 weeks and 8 days respectively. 4. Simulations suggest that models assuming closure are sensitive to changes in occupancy. Power analyses further suggest that the modelling procedure we apply can effectively test for closure. 5. Synthesis and applications. Our demonstration that sites may be open to changes in site occupancy over time-scales typical of many occupancy investigations, combined with the sensitivity of models to violations of the closure assumption, highlights the importance of properly addressing the closure assumption in both sampling designs and analysis. Furthermore, inappropriately applying closed models could have negative consequences when monitoring rare or declining species for conservation and management decisions, because violations of closure typically lead to overestimates of the probability of occurrence.

Three-dimensional multi-scale model of deformable platelets adhesion to vessel wall in blood flow

PubMed Central

Wu, Ziheng; Xu, Zhiliang; Kim, Oleg; Alber, Mark

2014-01-01

When a blood vessel ruptures or gets inflamed, the human body responds by rapidly forming a clot to restrict the loss of blood. Platelets aggregation at the injury site of the blood vessel occurring via platelet–platelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. A novel three-dimensional multi-scale model is introduced and used in this paper to simulate receptor-mediated adhesion of deformable platelets at the site of vascular injury under different shear rates of blood flow. The novelty of the model is based on a new approach of coupling submodels at three biological scales crucial for the early clot formation: novel hybrid cell membrane submodel to represent physiological elastic properties of a platelet, stochastic receptor–ligand binding submodel to describe cell adhesion kinetics and lattice Boltzmann submodel for simulating blood flow. The model implementation on the GPU cluster significantly improved simulation performance. Predictive model simulations revealed that platelet deformation, interactions between platelets in the vicinity of the vessel wall as well as the number of functional GPIbα platelet receptors played significant roles in platelet adhesion to the injury site. Variation of the number of functional GPIbα platelet receptors as well as changes of platelet stiffness can represent effects of specific drugs reducing or enhancing platelet activity. Therefore, predictive simulations can improve the search for new drug targets and help to make treatment of thrombosis patient-specific. PMID:24982253

A site specific model and analysis of the neutral somatic mutation rate in whole-genome cancer data.

PubMed

Bertl, Johanna; Guo, Qianyun; Juul, Malene; Besenbacher, Søren; Nielsen, Morten Muhlig; Hornshøj, Henrik; Pedersen, Jakob Skou; Hobolth, Asger

2018-04-19

Detailed modelling of the neutral mutational process in cancer cells is crucial for identifying driver mutations and understanding the mutational mechanisms that act during cancer development. The neutral mutational process is very complex: whole-genome analyses have revealed that the mutation rate differs between cancer types, between patients and along the genome depending on the genetic and epigenetic context. Therefore, methods that predict the number of different types of mutations in regions or specific genomic elements must consider local genomic explanatory variables. A major drawback of most methods is the need to average the explanatory variables across the entire region or genomic element. This procedure is particularly problematic if the explanatory variable varies dramatically in the element under consideration. To take into account the fine scale of the explanatory variables, we model the probabilities of different types of mutations for each position in the genome by multinomial logistic regression. We analyse 505 cancer genomes from 14 different cancer types and compare the performance in predicting mutation rate for both regional based models and site-specific models. We show that for 1000 randomly selected genomic positions, the site-specific model predicts the mutation rate much better than regional based models. We use a forward selection procedure to identify the most important explanatory variables. The procedure identifies site-specific conservation (phyloP), replication timing, and expression level as the best predictors for the mutation rate. Finally, our model confirms and quantifies certain well-known mutational signatures. We find that our site-specific multinomial regression model outperforms the regional based models. The possibility of including genomic variables on different scales and patient specific variables makes it a versatile framework for studying different mutational mechanisms. Our model can serve as the neutral null model for the mutational process; regions that deviate from the null model are candidates for elements that drive cancer development.

DEVELOP MULTI-STRESSOR, OPEN ARCHITECTURE MODELING FRAMEWORK FOR ECOLOGICAL EXPOSURE FROM SITE TO WATERSHED SCALE

EPA Science Inventory

A number of multimedia modeling frameworks are currently being developed. The Multimedia Integrated Modeling System (MIMS) is one of these frameworks. A framework should be seen as more of a multimedia modeling infrastructure than a single software system. This infrastructure do...

New datasets for quantifying snow-vegetation-atmosphere interactions in boreal birch and conifer forests

NASA Astrophysics Data System (ADS)

Reid, T. D.; Essery, R.; Rutter, N.; Huntley, B.; Baxter, R.; Holden, R.; King, M.; Hancock, S.; Carle, J.

2012-12-01

Boreal forests exert a strong influence on weather and climate by modifying the surface energy and radiation balance. However, global climate and numerical weather prediction models use forest parameter values from simple look-up tables or maps that are derived from limited satellite data, on large grid scales. In reality, Arctic landscapes are inherently heterogeneous, with highly variable land cover types and structures on a variety of spatial scales. There is value in collecting detailed field data for different areas of vegetation cover, to assess the accuracy of large-scale assumptions. To address these issues, a consortium of researchers funded by the UK's Natural Environment Research Council have collected extensive data on radiation, meteorology, snow cover and canopy structure at two contrasting Arctic forest sites. The chosen study sites were an area of boreal birch forest near Abisko, Sweden in March/April 2011 and mixed conifer forest at Sodankylä, Finland in March/April 2012. At both sites, arrays comprising ten shortwave pyranometers and four longwave pyrgeometers were deployed for periods of up to 50 days, under forest plots of varying canopy structures and densities. In addition, downwelling longwave irradiance and global and diffuse shortwave irradiances were recorded at nearby open sites representing the top-of-canopy conditions. Meteorological data were recorded at all sub-canopy and open sites using automatic weather stations. Over the same periods, tree skin temperatures were measured on selected trees using contact thermocouples, infrared thermocouples and thermal imagery. Canopy structure was accurately quantified through manual surveys, extensive hemispherical photography and terrestrial laser scans of every study plot. Sub-canopy snow depth and snow water equivalent were measured on fine-scale grids at each study plot. Regular site maintenance ensured a high quality dataset covering the important Arctic spring period. The data have several applications, for example in forest ecology, canopy radiative transfer models, snow hydrological modelling, and land surface schemes, for a variety of canopy types from sparse, leafless birch to dense pine and spruce. The work also allows the comparison of modern, highly detailed methods such as laser scanning and thermal imagery with older, well-established data collection methods. By combining these data with airborne and satellite remote sensing data, snow-vegetation-atmosphere interactions could be estimated over a wide area of the heterogeneous boreal landscape. This could improve estimates of crucial parameters such as land surface albedo on the grid scales required for global or regional weather and climate models.

Multisite comparison of drivers of methane emissions from wetlands in the European Arctic: influence of vegetation community and water table.

NASA Astrophysics Data System (ADS)

Dinsmore, Kerry; Drewer, Julia; Leeson, Sarah; Skiba, Ute; Levy, Pete; George, Charles

2014-05-01

Arctic and sub arctic wetlands are a major source of atmospheric CH4 and therefore have the potential to be important in controlling global radiative forcing. Furthermore, the strong links between wetland CH4 emissions and vegetation community, hydrology and temperature suggest potentially large feedbacks between climate change and future emissions. Quantifying current emissions over large spatial scales and predicting future climatic feedbacks requires a fundamental understanding of the ground based drivers of plot scale emissions. The MAMM project (Methane in the Arctic: Measurements and Modelling) aims to understand and quantify current CH4 emissions and future climatic impacts by combining both ground and aircraft measurements across the European Arctic with regional computer modelling. Here we present results from the ground-based MAMM measurement campaigns, analysing chamber-measured CH4 emissions from two sites in the European Arctic/Sub-Arctic region (Sodankylä, Finland; Stordalen Mire, Sweden) from growing seasons in 2012 and 2013. A total of 85 wetland static chambers were deployed across the two field sites; 39 at Sodankylä (67° 22'01' N, 26° 3'06' E) in 2012 and 46 at Stordalen Mire (68° 21'20' N, 19° 02'56' E) in 2013. Chamber design, protocol and deployment were the same across both sites. Chambers were located at sites chosen strategically to cover the local range of water table depths and vegetation communities. A total of 18 and 15 repeated measurements were made at each chamber in Sodankylä and Stordalen Mire, respectively, over the snow-free season. Preliminary results show a large range of CH4 fluxes across both sites ranging from a CH4 uptake of up to 0.07 and 0.06 mg CH4-C m-2 hr-1 to emissions of 17.3 and 44.2 mg CH4-C m-2 hr-1 in Sodankylä and Stordalen Mire, respectively. Empirical models based on vegetation community, water table depth, temperature and soil nutrient availability (Plant Root Simulator Probes, PRSTM) have been constructed with the aim of understanding the drivers of chamber scale fluxes. By combining measurements made at two different sites, >300km apart, using the same experimental setup, we are uniquely able to investigate whether CH4 emissions are driven by common parameters. Furthermore we are able to determine if plot scale empirical models and parameterisations can be used effectively to upscale emissions to landscape and whole Arctic scale.

Estimating recharge at Yucca Mountain, Nevada, USA: Comparison of methods

USGS Publications Warehouse

Flint, A.L.; Flint, L.E.; Kwicklis, E.M.; Fabryka-Martin, J. T.; Bodvarsson, G.S.

2002-01-01

Obtaining values of net infiltration, groundwater travel time, and recharge is necessary at the Yucca Mountain site, Nevada, USA, in order to evaluate the expected performance of a potential repository as a containment system for high-level radioactive waste. However, the geologic complexities of this site, its low precipitation and net infiltration, with numerous mechanisms operating simultaneously to move water through the system, provide many challenges for the estimation of the spatial distribution of recharge. A variety of methods appropriate for arid environments has been applied, including water-balance techniques, calculations using Darcy's law in the unsaturated zone, a soil-physics method applied to neutron-hole water-content data, inverse modeling of thermal profiles in boreholes extending through the thick unsaturated zone, chloride mass balance, atmospheric radionuclides, and empirical approaches. These methods indicate that near-surface infiltration rates at Yucca Mountain are highly variable in time and space, with local (point) values ranging from zero to several hundred millimeters per year. Spatially distributed net-infiltration values average 5 mm/year, with the highest values approaching 20 mm/year near Yucca Crest. Site-scale recharge estimates range from less than 1 to about 12 mm/year. These results have been incorporated into a site-scale model that has been calibrated using these data sets that reflect infiltration processes acting on highly variable temporal and spatial scales. The modeling study predicts highly non-uniform recharge at the water table, distributed significantly differently from the non-uniform infiltration pattern at the surface.

Implications of two Holocene time-dependent geomagnetic models for cosmogenic nuclide production rate scaling

NASA Astrophysics Data System (ADS)

Lifton, Nathaniel

2016-01-01

The geomagnetic field is a major influence on in situ cosmogenic nuclide production rates at a given location (in addition to atmospheric pressure and, to a lesser extent, solar modulation effects). A better understanding of how past fluctuations in these influences affected production rates should allow more accurate application of cosmogenic nuclides. As such, this work explores the cosmogenic nuclide production rate scaling implications of two recent time-dependent spherical harmonic geomagnetic models spanning the Holocene. Korte and Constable (2011, Phys. Earth Planet. Inter.188, 247-259) and Korte et al. (2011, Earth Planet. Sci. Lett. 312, 497-505) recently updated earlier spherical harmonic paleomagnetic models with new paleomagnetic data from sediment cores in addition to new archeomagnetic and volcanic data. These updated models offer improved resolution and accuracy over the previous versions, in part due to increased temporal and spatial data coverage. In addition, Pavón-Carrasco et al. (2014, Earth Planet. Sci. Lett. 388, 98-109) developed another time-dependent spherical harmonic model of the Holocene geomagnetic field, based solely on archeomagnetic and volcanic paleomagnetic data from the same underlying paleomagnetic database as the Korte et al. models, but extending to 14 ka. With the new models as input, trajectory-traced estimates of effective vertical cutoff rigidity (RC - the standard method for ordering cosmic ray data) yield significantly different time-integrated scaling predictions when compared to each other and to results using the earlier models. In addition, predictions of each new model using RC are tested empirically using recently published production rate calibration data for both 10Be and 3He, and compared to predictions using corresponding time-varying geocentric dipolar RC formulations and a static geocentric axial dipole (GAD) model. Results for the few calibration sites from geomagnetically sensitive regions suggest that the Pavón-Carrasco et al. (2014) time-varying dipolar model tends to predict sea level, high latitude production rates more in line with those from calibration sites not affected by geomagnetic variations. This suggests that uncertainties arising from hemispheric and temporal sampling biases in the Holocene spherical harmonic models considered here, combined with the currently limited spatial and temporal distribution of production rate calibration sites as empirical tests, limit the robustness of the non-dipole aspects of these models for production rate scaling. These analyses should be revisited as such models improve and additional calibration sites become available.

Logistic regression accuracy across different spatial and temporal scales for a wide-ranging species, the marbled murrelet

Treesearch

Carolyn B. Meyer; Sherri L. Miller; C. John Ralph

2004-01-01

The scale at which habitat variables are measured affects the accuracy of resource selection functions in predicting animal use of sites. We used logistic regression models for a wide-ranging species, the marbled murrelet, (Brachyramphus marmoratus) in a large region in California to address how much changing the spatial or temporal scale of...

MODFLOW-LGR: Practical application to a large regional dataset

NASA Astrophysics Data System (ADS)

Barnes, D.; Coulibaly, K. M.

2011-12-01

In many areas of the US, including southwest Florida, large regional-scale groundwater models have been developed to aid in decision making and water resources management. These models are subsequently used as a basis for site-specific investigations. Because the large scale of these regional models is not appropriate for local application, refinement is necessary to analyze the local effects of pumping wells and groundwater related projects at specific sites. The most commonly used approach to date is Telescopic Mesh Refinement or TMR. It allows the extraction of a subset of the large regional model with boundary conditions derived from the regional model results. The extracted model is then updated and refined for local use using a variable sized grid focused on the area of interest. MODFLOW-LGR, local grid refinement, is an alternative approach which allows model discretization at a finer resolution in areas of interest and provides coupling between the larger "parent" model and the locally refined "child." In the present work, these two approaches are tested on a mining impact assessment case in southwest Florida using a large regional dataset (The Lower West Coast Surficial Aquifer System Model). Various metrics for performance are considered. They include: computation time, water balance (as compared to the variable sized grid), calibration, implementation effort, and application advantages and limitations. The results indicate that MODFLOW-LGR is a useful tool to improve local resolution of regional scale models. While performance metrics, such as computation time, are case-dependent (model size, refinement level, stresses involved), implementation effort, particularly when regional models of suitable scale are available, can be minimized. The creation of multiple child models within a larger scale parent model makes it possible to reuse the same calibrated regional dataset with minimal modification. In cases similar to the Lower West Coast model, where a model is larger than optimal for direct application as a parent grid, a combination of TMR and LGR approaches should be used to develop a suitable parent grid.

COSP - A computer model of cyclic oxidation

NASA Technical Reports Server (NTRS)

Lowell, Carl E.; Barrett, Charles A.; Palmer, Raymond W.; Auping, Judith V.; Probst, Hubert B.

1991-01-01

A computer model useful in predicting the cyclic oxidation behavior of alloys is presented. The model considers the oxygen uptake due to scale formation during the heating cycle and the loss of oxide due to spalling during the cooling cycle. The balance between scale formation and scale loss is modeled and used to predict weight change and metal loss kinetics. A simple uniform spalling model is compared to a more complex random spall site model. In nearly all cases, the simpler uniform spall model gave predictions as accurate as the more complex model. The model has been applied to several nickel-base alloys which, depending upon composition, form Al2O3 or Cr2O3 during oxidation. The model has been validated by several experimental approaches. Versions of the model that run on a personal computer are available.

Economic decision making and the application of nonparametric prediction models

USGS Publications Warehouse

Attanasi, E.D.; Coburn, T.C.; Freeman, P.A.

2007-01-01

Sustained increases in energy prices have focused attention on gas resources in low permeability shale or in coals that were previously considered economically marginal. Daily well deliverability is often relatively small, although the estimates of the total volumes of recoverable resources in these settings are large. Planning and development decisions for extraction of such resources must be area-wide because profitable extraction requires optimization of scale economies to minimize costs and reduce risk. For an individual firm the decision to enter such plays depends on reconnaissance level estimates of regional recoverable resources and on cost estimates to develop untested areas. This paper shows how simple nonparametric local regression models, used to predict technically recoverable resources at untested sites, can be combined with economic models to compute regional scale cost functions. The context of the worked example is the Devonian Antrim shale gas play, Michigan Basin. One finding relates to selection of the resource prediction model to be used with economic models. Models which can best predict aggregate volume over larger areas (many hundreds of sites) may lose granularity in the distribution of predicted volumes at individual sites. This loss of detail affects the representation of economic cost functions and may affect economic decisions. Second, because some analysts consider unconventional resources to be ubiquitous, the selection and order of specific drilling sites may, in practice, be determined by extraneous factors. The paper also shows that when these simple prediction models are used to strategically order drilling prospects, the gain in gas volume over volumes associated with simple random site selection amounts to 15 to 20 percent. It also discusses why the observed benefit of updating predictions from results of new drilling, as opposed to following static predictions, is somewhat smaller. Copyright 2007, Society of Petroleum Engineers.

Verification of geomechanical integrity and prediction of long-term mineral trapping for the Ketzin CO2 storage pilot site

NASA Astrophysics Data System (ADS)

Kempka, Thomas; De Lucia, Marco; Kühn, Michael

2014-05-01

Static and dynamic numerical modelling generally accompany the entire CO2 storage site life cycle. Thereto, it is required to match the employed models with field observations on a regular basis in order to predict future site behaviour. We investigated the coupled processes at the Ketzin CO2 storage pilot site [1] using a model coupling concept focusing on the temporal relevance of processes involved (hydraulic, chemical and mechanical) at given time-scales (site operation, abandonment and long-term stabilization). For that purpose, long-term dynamic multi-phase flow simulations [2], [3] established the basis for all simulations discussed in the following. Hereby, pressure changes resulting in geomechanical effects are largest during site operation, whereas geochemical reactions are governed by slow kinetics resulting in a long-term stabilization. To account for mechanical integrity, which may be mainly affected during site operation, we incorporated a regional-scale coupled hydro-mechanical model. Our simulation results show maximum ground surface displacements of about 4 mm, whereas shear and tensile failure are not observed. Consequently, the CO2 storage operation at the Ketzin pilot site does not compromise reservoir, caprock and fault integrity. Chemical processes responsible for mineral trapping are expected to mainly occur during long-term stabilization at the Ketzin pilot site [4]. Hence, our previous assessment [3] was extended by integrating two long-term mineral trapping scenarios. Thereby, mineral trapping contributes to the trapping mechanisms with 11.7 % after 16,000 years of simulation in our conservative and with 30.9 % in our maximum reactivity scenarios. Dynamic flow simulations indicate that only 0.2 % of the CO2 injected (about 67,270 t CO2 in total) is in gaseous state, but structurally trapped after 16,000 years. Depending on the studied long-term scenario, CO2 dissolution is the dominating trapping mechanism with 68.9 % and 88.1 %, respectively. We verified the mechanical integrity of the storage system during site operation and predicted the trapping mechanisms for the Ketzin pilot site based on a time-dependent integration of relevant processes for a time period of 16,000 years. Supported by our coupled modelling results, we conclude that CO2 storage at the Ketzin site is safe and reliable on the pilot scale. References [1] Martens, S., Kempka, T., Liebscher, A., Lüth, S., Möller, F., Myrttinen, A., Norden, B., Schmidt-Hattenberger, C., Zimmer, M., Kühn, M. Europe's longest-operating on-shore CO2 storage site at Ketzin, Germany: a progress report after three years of injection. Environmental Earth Sciences 2012 67(2): 323-334. [2] Kempka, T., Kühn, M. Numerical simulations of CO2 arrival times and reservoir pressure coincide with observations from the Ketzin pilot site, Germany. Environmental Earth Sciences 2013 70(8): 3675-3685. [3] Kempka, T., Klein, E., De Lucia, M., Tillner, E., Kühn, M. Assessment of Long-term CO2 Trapping Mechanisms at the Ketzin Pilot Site (Germany) by Coupled Numerical Modelling. Energy Procedia 2013 37: 5419-5426. [4] Klein, E., De Lucia, M., Kempka, T., Kühn, M. Evaluation of long-term mineral trapping at the Ketzin pilot site for CO2 storage: An integrative approach using geochemical modelling and reservoir simulation. International Journal of Greenhouse Gas Control 2013 19: 720-730.

Hydrogeology of the unsaturated zone, North Ramp area of the Exploratory Studies Facility, Yucca Mountain, Nevada

USGS Publications Warehouse

Rousseau, Joseph P.; Kwicklis, Edward M.; Gillies, Daniel C.; Rousseau, Joseph P.; Kwicklis, Edward M.; Gillies, Daniel C.

1999-01-01

Yucca Mountain, in southern Nevada, is being investigated by the U.S. Department of Energy as a potential site for a repository for high-level radioactive waste. This report documents the results of surface-based geologic, pneumatic, hydrologic, and geochemical studies conducted during 1992 to 1996 by the U.S. Geological Survey in the vicinity of the North Ramp of the Exploratory Studies Facility (ESF) that are pertinent to understanding multiphase fluid flow within the deep unsaturated zone. Detailed stratigraphic and structural characteristics of the study area provided the hydrogeologic framework for these investigations. Multiple lines of evidence indicate that gas flow and liquid flow within the welded tuffs of the unsaturated zone occur primarily through fractures. Fracture densities are highest in the Tiva Canyon welded (TCw) and Topopah Spring welded (TSw) hydrogeologic units. Although fracture density is much lower in the intervening nonwelded and bedded tuffs of the Paintbrush nonwelded hydrogeologic unit (PTn), pneumatic and aqueous-phase isotopic evidence indicates that substantial secondary permeability is present locally in the PTn, especially in the vicinity of faults. Borehole air-injection tests indicate that bulk air-permeability ranges from 3.5x10-14 to 5.4x10-11 square meters for the welded tuffs and from 1.2x10-13 to 3.0x10-12 square meters for the non welded and bedded tuffs of the PTn. Analyses of in-situ pneumatic-pressure data from monitored boreholes produced estimates of bulk permeability that were comparable to those determined from the air-injection tests. In many cases, both sets of estimates are two to three orders of magnitude larger than estimates based on laboratory analyses of unfractured core samples. The in-situ pneumatic-pressure records also indicate that the unsaturated-zone pneumatic system consists of four subsystems that coincide with the four major hydrogeologic units of the unsaturated zone at Yucca Mountain. In descending order, these hydrogeologic units are the Tiva Canyon welded (TCw), Paintbrush nonwelded (PTn), Topopah Spring welded (TSw ), and Calico Hills nonwelded (CHn). Deep percolation takes place as episodic pulses of inflow that propagate rapidly to depth and apparently bypass most of the rock matrix. Field-scale and core-scale water potentials throughout much of the PTn and TSw are very high, generally greater than -0.3 megapascals, and are nearly depth invariant. Thus, the imbibition capacity of the densely welded tuffs, at least near fractures, is very small because of low matrix permeabilities and low water-potential gradients across the fracture-matrix interface. The combination of high fracture permeability, high water potentials, high matrix saturations, and low matrix permeabilities results in a percolation environment that favors deep fracture flow. The episodic pulses of inflow are evidenced in the sporadic but nevertheless commonplace occurrence of water with concentrations of radioactive isotopes indicative of origins postdating the atmospheric testing of nuclear weapons. High concentrations of tritium have been detected at many horizons within the PTn and in the top of the TSw. Much lower concentrations of tritium, indicating the mixing of a bomb-pulse component with older water, have been detected in the deeper sections of the TSw and in the CHn. Evidence for fracture flow also is apparent in the widespread occurrence of perched water with chemical and isotopic signatures that indicate a fracture-flow origin for at least some of this water. In the North Ramp area, perched water has been detected at the base of the Topopah Spring Tuff or in the top of the underlying non welded to partially welded tuffs of the Calico Hills Formation in every dry-drilled borehole of sufficient depth to penetrate the Topopah Spring Tuff-Calico Hills Formation contact. The concentrations of the major ions of the perched water are similar to that of TSw pore water at borehole UZ-14, CHn pore water, and saturated-zone water at boreholes NRG-7 a and SD-9. The absolute chloride concentration of the perched water, however, is much lower than the chloride concentration of pore water from either the PTn or the TSw. The chemical and isotopic compositions of perched water indicate that this water was derived primarily from fracture flow, with little or no contribution from water in the matrix of the overlying rock. Carbon-14 ages of perched water range from 3,000 to 7,000 years. Strontium-87 isotope ratios indicate dissolution of surficial pedogenic calcite and calcite fracture fillings, which supports a fracture-flow origin for perched water. Moreover, carbon-13 and deuterium isotope values indicate rapid infiltration into fractures with little or no prior evaporation. Evidence for deep fracture flow into the Calico Hills Formation at UZ-14 is indicated by carbon-14 values that are from 65 and 95 percent modem carbon, equivalent to apparent ages of about 3,500 to 500 years. Some of these ages are younger than age estimates for perched water in the overlying Topopah Spring Tuff and are much younger than any that could be derived from a matrix-flow model. Evidence is lacking for extensive lateral flow within the PTn or for interception and diversion of this flow downward along structural pathways (faults), two key features of the original conceptual model for unsaturated flow at Yucca Mountain. Where data are available to infer lateral flow in the PTn, it is not certain that fracture flow could not have produced the same results. Pneumatic data, derived primarily from analysis of the interference effects from excavation of the North Ramp tunnel, indicate that faults within the Topopah Spring Tuff are open over substantial distances and are very permeable. Tunnel-boring-induced pneumatic disturbances have been propagated along these faults over distances that exceed 500 meters. These disturbances also have been detected in the pneumatic-pressure record of the overlying PTn in the vicinity of these faults. In spite of the apparent high permeability of faults, the existing data have neither confirmed nor refuted the hypothetical role of these faults in intercepting lateral flow from within or from above the PTn and diverting this flow downward into the deeper subsurface. On the basis of measured temperature gradients within the TSw, deep percolation appears to be greatest beneath active channels of major drainages, diminishing toward the margins and hillslopes bordering these channels. Numerical simulations indicate that this downward percolation is accompanied by lateral spreading as the percolation front moves downward through the PTn and across the contact between the PTn and underlying TSw. Temperature data from a well-documented site in Pagany Wash indicate the presence of a significant heat-flow deficit between the PTn and underlying TSw that most likely is due to nonconductive heat-flow processes with substantial capacity to extract heat. Percolation fluxes on the order of 10 to 20 millimeters per year beneath the Pagany Wash channel and on the order of 5 millimeters per year or less beneath the hillslopes bordering this drainage accounted for the apparent heat-flow deficit. Analyses of borehole temperature gradients in Drill Hole Wash indicate similar percolation fluxes and flux distributions within that drainage. An analysis of residence times estimated from uncorrected carbon-14 activities of perched-water samples and estimates for the volume of the structurally controlled reservoir, however, showed that the perched-water reservoir intersected by borehole UZ-14 under Drill Hole Wash could be sustained by percolation fluxes through the TSw of as little as 0.001 to 0.29 millimeter per year. The significance and implications of these findings with respect to waste isolation are discussed in the appendix of this report.

Integrating fine-scale soil data into species distribution models: preparing Soil Survey Geographic (SSURGO) data from multiple counties

Treesearch

Matthew P. Peters; Louis R. Iverson; Anantha M. Prasad; Steve N. Matthews

2013-01-01

Fine-scale soil (SSURGO) data were processed at the county level for 37 states within the eastern United States, initially for use as predictor variables in a species distribution model called DISTRIB II. Values from county polygon files converted into a continuous 30-m raster grid were aggregated to 4-km cells and integrated with other environmental and site condition...

Combining Deterministic structures and stochastic heterogeneity for transport modeling

NASA Astrophysics Data System (ADS)

Zech, Alraune; Attinger, Sabine; Dietrich, Peter; Teutsch, Georg

2017-04-01

Contaminant transport in highly heterogeneous aquifers is extremely challenging and subject of current scientific debate. Tracer plumes often show non-symmetric but highly skewed plume shapes. Predicting such transport behavior using the classical advection-dispersion-equation (ADE) in combination with a stochastic description of aquifer properties requires a dense measurement network. This is in contrast to the available information for most aquifers. A new conceptual aquifer structure model is presented which combines large-scale deterministic information and the stochastic approach for incorporating sub-scale heterogeneity. The conceptual model is designed to allow for a goal-oriented, site specific transport analysis making use of as few data as possible. Thereby the basic idea is to reproduce highly skewed tracer plumes in heterogeneous media by incorporating deterministic contrasts and effects of connectivity instead of using unimodal heterogeneous models with high variances. The conceptual model consists of deterministic blocks of mean hydraulic conductivity which might be measured by pumping tests indicating values differing in orders of magnitudes. A sub-scale heterogeneity is introduced within every block. This heterogeneity can be modeled as bimodal or log-normal distributed. The impact of input parameters, structure and conductivity contrasts is investigated in a systematic manor. Furthermore, some first successful implementation of the model was achieved for the well known MADE site.

Lessons Learned from Near Field Modeling and Data Collected at the SPE Chemical Explosions in Jointed Rock Masses

NASA Astrophysics Data System (ADS)

Vorobiev, O.; Ezzedine, S. M.; Hurley, R.; Antoun, T.; Glenn, L.

2016-12-01

This work describes the near-field modeling of wave propagation from underground chemicalexplosions conducted at the Nevada National Security Site (NNSS) in fractured granitic rock. Lab testsperformed on granite samples excavated from various locations at the SPE site have shown littlevariability in mechanical properties. Granite at this scale can be considered as an isotropic medium. Wehave shown, however, that on the scale of the pressure waves generated during chemical explosions(tens of meters), the effective mechanical properties may vary significantly and exhibit both elastic andplastic anisotropies due to local variations in joint properties such as spacing orientation, joint aperture,cohesion and saturation. Since including every joint in a discrete fashion in computational model is notfeasible, especially for large-scale calculations ( 1.5 km domain), we have developed a computationaltechnique to upscale mechanical properties for various scales (frequencies) using geophysicalcharacterization conducted during recent SPE tests at the NNSS. Stochastic representation of thesefeatures based on the field characterizations has been implemented into LLNL's Geodyn-L hydrocode.Scale dependency in mechanical properties is important in order to understand how the ground motionscales with yield. We hope that such an approach will not only provide a better prediction of theground motion observed in the SPE (where the yield varies from 100 kg to few tons of TNT equivalent)but also will allow us to extrapolate results of the SPE to sources with bigger yields. We have validatedour computational results by comparing the measured and computed ground motion at various rangesfor experiments of various yields (SPE1-SPE5). Using the new model we performed severalcomputational studies to identify the most important mechanical properties of the rock mass specific tothe SPE site and to understand their roles in the observed ground motion in the near-field. We willpresent a series of lessons learned from the data gathered at the NNSS SPE site and the simulationsconducted using state-of-the-art HPC codes.This work performed under the auspices of the U.S. Department of Energy by Lawrence LivermoreNational Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-679820

Assessing FPAR Source and Parameter Optimization Scheme in Application of a Diagnostic Carbon Flux Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, D P; Ritts, W D; Wharton, S

2009-02-26

The combination of satellite remote sensing and carbon cycle models provides an opportunity for regional to global scale monitoring of terrestrial gross primary production, ecosystem respiration, and net ecosystem production. FPAR (the fraction of photosynthetically active radiation absorbed by the plant canopy) is a critical input to diagnostic models, however little is known about the relative effectiveness of FPAR products from different satellite sensors nor about the sensitivity of flux estimates to different parameterization approaches. In this study, we used multiyear observations of carbon flux at four eddy covariance flux tower sites within the conifer biome to evaluate these factors.more » FPAR products from the MODIS and SeaWiFS sensors, and the effects of single site vs. cross-site parameter optimization were tested with the CFLUX model. The SeaWiFs FPAR product showed greater dynamic range across sites and resulted in slightly reduced flux estimation errors relative to the MODIS product when using cross-site optimization. With site-specific parameter optimization, the flux model was effective in capturing seasonal and interannual variation in the carbon fluxes at these sites. The cross-site prediction errors were lower when using parameters from a cross-site optimization compared to parameter sets from optimization at single sites. These results support the practice of multisite optimization within a biome for parameterization of diagnostic carbon flux models.« less

Scale-Dependent Rates of Uranyl Surface Complexation Reaction in Sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chongxuan; Shang, Jianying; Kerisit, Sebastien N.

Scale-dependency of uranyl[U(VI)] surface complexation rates was investigated in stirred flow-cell and column systems using a U(VI)-contaminated sediment from the US Department of Energy, Hanford site, WA. The experimental results were used to estimate the apparent rate of U(VI) surface complexation at the grain-scale and in porous media. Numerical simulations using molecular, pore-scale, and continuum models were performed to provide insights into and to estimate the rate constants of U(VI) surface complexation at the different scales. The results showed that the grain-scale rate constant of U(VI) surface complexation was over 3 to 10 orders of magnitude smaller, dependent on themore » temporal scale, than the rate constant calculated using the molecular simulations. The grain-scale rate was faster initially and slower with time, showing the temporal scale-dependency. The largest rate constant at the grain-scale decreased additional 2 orders of magnitude when the rate was scaled to the porous media in the column. The scaling effect from the grain-scale to the porous media became less important for the slower sorption sites. Pore-scale simulations revealed the importance of coupled mass transport and reactions in both intragranular and inter-granular domains, which caused both spatial and temporal dependence of U(VI) surface complexation rates in the sediment. Pore-scale simulations also revealed a new rate-limiting mechanism in the intragranular porous domains that the rate of coupled diffusion and surface complexation reaction was slower than either process alone. The results provided important implications for developing models to scale geochemical/biogeochemical reactions.« less

Modelling hurricane exposure and wind speed on a mesoclimate scale: a case study from Cusuco NP, Honduras.

PubMed

Batke, Sven P; Jocque, Merlijn; Kelly, Daniel L

2014-01-01

High energy weather events are often expected to play a substantial role in biotic community dynamics and large scale diversity patterns but their contribution is hard to prove. Currently, observations are limited to the documentation of accidental records after the passing of such events. A more comprehensive approach is synthesising weather events in a location over a long time period, ideally at a high spatial resolution and on a large geographic scale. We provide a detailed overview on how to generate hurricane exposure data at a meso-climate level for a specific region. As a case study we modelled landscape hurricane exposure in Cusuco National Park (CNP), Honduras with a resolution of 50 m×50 m patches. We calculated actual hurricane exposure vulnerability site scores (EVVS) through the combination of a wind pressure model, an exposure model that can incorporate simple wind dynamics within a 3-dimensional landscape and the integration of historical hurricanes data. The EVSS was calculated as a weighted function of sites exposure, hurricane frequency and maximum wind velocity. Eleven hurricanes were found to have affected CNP between 1995 and 2010. The highest EVSS's were predicted to be on South and South-East facing sites of the park. Ground validation demonstrated that the South-solution (i.e. the South wind inflow direction) explained most of the observed tree damage (90% of the observed tree damage in the field). Incorporating historical data to the model to calculate actual hurricane exposure values, instead of potential exposure values, increased the model fit by 50%.

Modelling Hurricane Exposure and Wind Speed on a Mesoclimate Scale: A Case Study from Cusuco NP, Honduras

PubMed Central

Batke, Sven P.; Jocque, Merlijn; Kelly, Daniel L.

2014-01-01

High energy weather events are often expected to play a substantial role in biotic community dynamics and large scale diversity patterns but their contribution is hard to prove. Currently, observations are limited to the documentation of accidental records after the passing of such events. A more comprehensive approach is synthesising weather events in a location over a long time period, ideally at a high spatial resolution and on a large geographic scale. We provide a detailed overview on how to generate hurricane exposure data at a meso-climate level for a specific region. As a case study we modelled landscape hurricane exposure in Cusuco National Park (CNP), Honduras with a resolution of 50 m×50 m patches. We calculated actual hurricane exposure vulnerability site scores (EVVS) through the combination of a wind pressure model, an exposure model that can incorporate simple wind dynamics within a 3-dimensional landscape and the integration of historical hurricanes data. The EVSS was calculated as a weighted function of sites exposure, hurricane frequency and maximum wind velocity. Eleven hurricanes were found to have affected CNP between 1995 and 2010. The highest EVSS’s were predicted to be on South and South-East facing sites of the park. Ground validation demonstrated that the South-solution (i.e. the South wind inflow direction) explained most of the observed tree damage (90% of the observed tree damage in the field). Incorporating historical data to the model to calculate actual hurricane exposure values, instead of potential exposure values, increased the model fit by 50%. PMID:24614168

Lower limb estimation from sparse landmarks using an articulated shape model.

PubMed

Zhang, Ju; Fernandez, Justin; Hislop-Jambrich, Jacqui; Besier, Thor F

2016-12-08

Rapid generation of lower limb musculoskeletal models is essential for clinically applicable patient-specific gait modeling. Estimation of muscle and joint contact forces requires accurate representation of bone geometry and pose, as well as their muscle attachment sites, which define muscle moment arms. Motion-capture is a routine part of gait assessment but contains relatively sparse geometric information. Standard methods for creating customized models from motion-capture data scale a reference model without considering natural shape variations. We present an articulated statistical shape model of the left lower limb with embedded anatomical landmarks and muscle attachment regions. This model is used in an automatic workflow, implemented in an easy-to-use software application, that robustly and accurately estimates realistic lower limb bone geometry, pose, and muscle attachment regions from seven commonly used motion-capture landmarks. Estimated bone models were validated on noise-free marker positions to have a lower (p=0.001) surface-to-surface root-mean-squared error of 4.28mm, compared to 5.22mm using standard isotropic scaling. Errors at a variety of anatomical landmarks were also lower (8.6mm versus 10.8mm, p=0.001). We improve upon standard lower limb model scaling methods with shape model-constrained realistic bone geometries, regional muscle attachment sites, and higher accuracy. Copyright © 2016 Elsevier Ltd. All rights reserved.

The 300 Area Integrated Field Research Challenge Quality Assurance Project Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fix, N. J.

Pacific Northwest National Laboratory and a group of expert collaborators are using the U.S. Department of Energy Hanford Site 300 Area uranium plume within the footprint of the 300-FF-5 groundwater operable unit as a site for an Integrated Field-Scale Subsurface Research Challenge (IFRC). The IFRC is entitled Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on the Hanford Site 300 Area Uranium Plume Project. The theme is investigation of multi-scale mass transfer processes. A series of forefront science questions on mass transfer are posed for research that relate to the effect of spatial heterogeneities; themore » importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements/approaches needed to characterize and model a mass transfer-dominated system. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the 300 Area IFRC Project. This plan is designed to be used exclusively by project staff.« less

Innovative Field Methods for Characterizing the Hydraulic Properties of a Complex Fractured Rock Aquifer (Ploemeur, Brittany)

NASA Astrophysics Data System (ADS)

Bour, O.; Le Borgne, T.; Longuevergne, L.; Lavenant, N.; Jimenez-Martinez, J.; De Dreuzy, J. R.; Schuite, J.; Boudin, F.; Labasque, T.; Aquilina, L.

2014-12-01

Characterizing the hydraulic properties of heterogeneous and complex aquifers often requires field scale investigations at multiple space and time scales to better constrain hydraulic property estimates. Here, we present and discuss results from the site of Ploemeur (Brittany, France) where complementary hydrological and geophysical approaches have been combined to characterize the hydrogeological functioning of this highly fractured crystalline rock aquifer. In particular, we show how cross-borehole flowmeter tests, pumping tests and frequency domain analysis of groundwater levels allow quantifying the hydraulic properties of the aquifer at different scales. In complement, we used groundwater temperature as an excellent tracer for characterizing groundwater flow. At the site scale, measurements of ground surface deformation through long-base tiltmeters provide robust estimates of aquifer storage and allow identifying the active structures where groundwater pressure changes occur, including those acting during recharge process. Finally, a numerical model of the site that combines hydraulic data and groundwater ages confirms the geometry of this complex aquifer and the consistency of the different datasets. The Ploemeur site, which has been used for water supply at a rate of about 106 m3 per year since 1991, belongs to the French network of hydrogeological sites H+ and is currently used for monitoring groundwater changes and testing innovative field methods.

AFOSR Technical Report Summaries, October - December 1989

DTIC Science & Technology

1989-12-01

0 .0- 1. . - 0. tun a> %.U I L A~ La~ IL’ Ui +IC-~ ~ ~ - 3, - 1C6 .-0t " L VO 00C V .~~@ c 1nV) 13- S0-’ N E-L 15 - In1 In M- V *.inUZ EL- I- m45 v L...3 -0 0Z 0>.CJ - j Li 0 L O.V C) 0 a 1 0/ .Ou. <- C U L- L 0 r- X A L 0 PIx -- 0 n> 0 La -- . < D- 0 zAW m z u 0 . E U Ul I- a . u0-. Im U 1-W0L N U r

Definite Project Report for Section 205 Flood Control, Illinois River, Liverpool, Illinois, with Final Environmental Impact Statement

DTIC Science & Technology

1989-10-01

consisting of fat clay, sandy lean clay, and clayey sand. 7 Climate The climate of Fulton County is humid continental and is characterized by cold...Tp a. FAT Can U0I S go in on &- WI - WU. GAJm. In.~a Ts IPA a 0.2 ft 17. AW’U.Z I 9 £1 t som alsieIpm n lawe W. . MY4 CIA am a s V 0 WMO a~~~a ". MVU...feet of Cahokia alluvium. The alluvium is made up of 5 feet of fat clay overlying 4 feet of sandy lean clay. Indicated in situ shear strengths range

Installation Restoration Program (IRP), Phase II, Stage 1 - Problem Confirmation Study, Norton Air Force Base, San Bernardino, California. Volume 1. Technical Report.

DTIC Science & Technology

1985-07-01

protein, and AFFF (Air Force Firefighting Foam). The frequency of training exercises has varied considerably over the years. During the early 1970’s...Surface ’ Cement/ Bentonite Grout Bentonite Seal Sand Pack 1. Ground Water Elevation r Mamaur July 4.5, 194 * . FIGURE 3-9 WELL CONSTRUCTION SUMMARY, ZONE...e zzzzzzzzz z I z z Z 0 -. N N E-3 3 0 3 3 w 3 w 0 o z ~ zzzzzzzz z z z z E- 0 0 E- 0z zzzzzzzz zz aua E- 0 4 10 zw 3 E- z 0 0 U)z V fC InZ OE- 3

Assessing the ability of potential evapotranspiration models in capturing dynamics of evaporative demand across various biomes and climatic regimes with ChinaFLUX measurements

NASA Astrophysics Data System (ADS)

Zheng, Han; Yu, Guirui; Wang, Qiufeng; Zhu, Xianjin; Yan, Junhua; Wang, Huimin; Shi, Peili; Zhao, Fenghua; Li, Yingnian; Zhao, Liang; Zhang, Junhui; Wang, Yanfen

2017-08-01

Estimates of atmospheric evaporative demand have been widely required for a variety of hydrological analyses, with potential evapotranspiration (PET) being an important measure representing evaporative demand of actual vegetated surfaces under given metrological conditions. In this study, we assessed the ability of various PET models in capturing long-term (typically 2003-2011) dynamics of evaporative demand at eight ecosystems across various biomes and climatic regimes in China. Prior to assessing PET dynamics, we first examined the reasonability of fourteen PET models in representing the magnitudes of evaporative demand using eddy-covariance actual evapotranspiration (AET) as an indicator. Results showed that the robustness of the fourteen PET models differed somewhat across the sites, and only three PET models could produce reasonable magnitudes of evaporative demand (i.e., PET ≥ AET on average) for all eight sites, including the: (i) Penman; (ii) Priestly-Taylor and (iii) Linacre models. Then, we assessed the ability of these three PET models in capturing dynamics of evaporative demand by comparing the annual and seasonal trends in PET against the equivalent trends in AET and precipitation (P) for particular sites. Results indicated that nearly all the three PET models could faithfully reproduce the dynamics in evaporative demand for the energy-limited conditions at both annual and seasonal scales, while only the Penman and Linacre models could represent dynamics in evaporative demand for the water-limited conditions. However, the Linacre model was unable to reproduce the seasonal switches between water- and energy-limited states for some sites. Our findings demonstrated that the choice of PET models would be essential for the evaporative demand analyses and other related hydrological analyses at different temporal and spatial scales.

Scale-dependent associations of Band-tailed Pigeon counts at mineral sites

USGS Publications Warehouse

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

2010-01-01

The abundance of Band-tailed Pigeons (Patagioenas fasciata monilis) has declined substantially from historic numbers along the Pacific Coast. Identification of patterns and causative factors of this decline are hampered because habitat use data are limited, and temporal and spatial variability patterns associated with population indices are not known. Furthermore, counts are influenced not only by pigeon abundance but also by rate of visitation to mineral sites, which may not be consistent. To address these issues, we conducted mineral site counts during 2001 and 2002 at 20 locations from 4 regions in the Pacific Northwest, including central Oregon and western Washington, USA, and British Columbia, Canada. We developed inference models that consisted of environmental factors and spatial characteristics at multiple spatial scales. Based on information theory, we compared models within a final set that included variables measured at 3 spatial scales (0.03 ha, 3.14 ha, and 7850 ha). Pigeon counts increased from central Oregon through northern Oregon and decreased into British Columbia. After accounting for this spatial pattern, we found that pigeon counts increased 12% ± 2.7 with a 10% increase in the amount of deciduous forested area within 100 m from a mineral site. Also, distance from the mineral site of interest to the nearest known mineral site was positively related to pigeon counts. These findings provide direction for future research focusing on understanding the relationships between indices of relative abundance and complete counts (censuses) of pigeon populations by identifying habitat characteristics that might influence visitation rates. Furthermore, our results suggest that spatial arrangement of mineral sites influences Band-tailed Pigeon counts and the populations which those counts represent.

Performance of Linear and Nonlinear Two-Leaf Light Use Efficiency Models at Different Temporal Scales

DOE PAGES

Wu, Xiaocui; Ju, Weimin; Zhou, Yanlian; ...

2015-02-25

The reliable simulation of gross primary productivity (GPP) at various spatial and temporal scales is of significance to quantifying the net exchange of carbon between terrestrial ecosystems and the atmosphere. This study aimed to verify the ability of a nonlinear two-leaf model (TL-LUEn), a linear two-leaf model (TL-LUE), and a big-leaf light use efficiency model (MOD17) to simulate GPP at half-hourly, daily and 8-day scales using GPP derived from 58 eddy-covariance flux sites in Asia, Europe and North America as benchmarks. Model evaluation showed that the overall performance of TL-LUEn was slightly but not significantly better than TL-LUE at half-hourlymore » and daily scale, while the overall performance of both TL-LUEn and TL-LUE were significantly better (p < 0.0001) than MOD17 at the two temporal scales. The improvement of TL-LUEn over TL-LUE was relatively small in comparison with the improvement of TL-LUE over MOD17. However, the differences between TL-LUEn and MOD17, and TL-LUE and MOD17 became less distinct at the 8-day scale. As for different vegetation types, TL-LUEn and TL-LUE performed better than MOD17 for all vegetation types except crops at the half-hourly scale. At the daily and 8-day scales, both TL-LUEn and TL-LUE outperformed MOD17 for forests. However, TL-LUEn had a mixed performance for the three non-forest types while TL-LUE outperformed MOD17 slightly for all these non-forest types at daily and 8-day scales. The better performance of TL-LUEn and TL-LUE for forests was mainly achieved by the correction of the underestimation/overestimation of GPP simulated by MOD17 under low/high solar radiation and sky clearness conditions. TL-LUEn is more applicable at individual sites at the half-hourly scale while TL-LUE could be regionally used at half-hourly, daily and 8-day scales. MOD17 is also an applicable option regionally at the 8-day scale.« less

Performance of Linear and Nonlinear Two-Leaf Light Use Efficiency Models at Different Temporal Scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Xiaocui; Ju, Weimin; Zhou, Yanlian

The reliable simulation of gross primary productivity (GPP) at various spatial and temporal scales is of significance to quantifying the net exchange of carbon between terrestrial ecosystems and the atmosphere. This study aimed to verify the ability of a nonlinear two-leaf model (TL-LUEn), a linear two-leaf model (TL-LUE), and a big-leaf light use efficiency model (MOD17) to simulate GPP at half-hourly, daily and 8-day scales using GPP derived from 58 eddy-covariance flux sites in Asia, Europe and North America as benchmarks. Model evaluation showed that the overall performance of TL-LUEn was slightly but not significantly better than TL-LUE at half-hourlymore » and daily scale, while the overall performance of both TL-LUEn and TL-LUE were significantly better (p < 0.0001) than MOD17 at the two temporal scales. The improvement of TL-LUEn over TL-LUE was relatively small in comparison with the improvement of TL-LUE over MOD17. However, the differences between TL-LUEn and MOD17, and TL-LUE and MOD17 became less distinct at the 8-day scale. As for different vegetation types, TL-LUEn and TL-LUE performed better than MOD17 for all vegetation types except crops at the half-hourly scale. At the daily and 8-day scales, both TL-LUEn and TL-LUE outperformed MOD17 for forests. However, TL-LUEn had a mixed performance for the three non-forest types while TL-LUE outperformed MOD17 slightly for all these non-forest types at daily and 8-day scales. The better performance of TL-LUEn and TL-LUE for forests was mainly achieved by the correction of the underestimation/overestimation of GPP simulated by MOD17 under low/high solar radiation and sky clearness conditions. TL-LUEn is more applicable at individual sites at the half-hourly scale while TL-LUE could be regionally used at half-hourly, daily and 8-day scales. MOD17 is also an applicable option regionally at the 8-day scale.« less

Model-data fusion across ecosystems: from multisite optimizations to global simulations

NASA Astrophysics Data System (ADS)

Kuppel, S.; Peylin, P.; Maignan, F.; Chevallier, F.; Kiely, G.; Montagnani, L.; Cescatti, A.

2014-11-01

This study uses a variational data assimilation framework to simultaneously constrain a global ecosystem model with eddy covariance measurements of daily net ecosystem exchange (NEE) and latent heat (LE) fluxes from a large number of sites grouped in seven plant functional types (PFTs). It is an attempt to bridge the gap between the numerous site-specific parameter optimization works found in the literature and the generic parameterization used by most land surface models within each PFT. The present multisite approach allows deriving PFT-generic sets of optimized parameters enhancing the agreement between measured and simulated fluxes at most of the sites considered, with performances often comparable to those of the corresponding site-specific optimizations. Besides reducing the PFT-averaged model-data root-mean-square difference (RMSD) and the associated daily output uncertainty, the optimization improves the simulated CO2 balance at tropical and temperate forests sites. The major site-level NEE adjustments at the seasonal scale are reduced amplitude in C3 grasslands and boreal forests, increased seasonality in temperate evergreen forests, and better model-data phasing in temperate deciduous broadleaf forests. Conversely, the poorer performances in tropical evergreen broadleaf forests points to deficiencies regarding the modelling of phenology and soil water stress for this PFT. An evaluation with data-oriented estimates of photosynthesis (GPP - gross primary productivity) and ecosystem respiration (Reco) rates indicates distinctively improved simulations of both gross fluxes. The multisite parameter sets are then tested against CO2 concentrations measured at 53 locations around the globe, showing significant adjustments of the modelled seasonality of atmospheric CO2 concentration, whose relevance seems PFT-dependent, along with an improved interannual variability. Lastly, a global-scale evaluation with remote sensing NDVI (normalized difference vegetation index) measurements indicates an improvement of the simulated seasonal variations of the foliar cover for all considered PFTs.

Wave resource variability: Impacts on wave power supply over regional to international scales

NASA Astrophysics Data System (ADS)

Smith, Helen; Fairley, Iain; Robertson, Bryson; Abusara, Mohammad; Masters, Ian

2017-04-01

The intermittent, irregular and variable nature of the wave energy resource has implications for the supply of wave-generated electricity into the grid. Intermittency of renewable power may lead to frequency and voltage fluctuations in the transmission and distribution networks. A matching supply of electricity must be planned to meet the predicted demand, leading to a need for gas-fired and back-up generating plants to supplement intermittent supplies, and potentially limiting the integration of intermittent power into the grid. Issues relating to resource intermittency and their mitigation through the development of spatially separated sites have been widely researched in the wind industry, but have received little attention to date in the less mature wave industry. This study analyses the wave resource over three different spatial scales to investigate the potential impacts of the temporal and spatial resource variability on the grid supply. The primary focus is the Southwest UK, a region already home to multiple existing and proposed wave energy test sites. Concurrent wave buoy data from six locations, supported by SWAN wave model hindcast data, are analysed to assess the correlation of the resource across the region and the variation in wave power with direction. Power matrices for theoretical nearshore and offshore devices are used to calculate the maximum step change in generated power across the region as the number of deployment sites is increased. The step change analysis is also applied across national and international spatial scales using output from the European Centre for Medium-range Weather Forecasting (ECMWF) ERA-Interim hindcast model. It is found that the deployment of multiple wave energy sites, whether on a regional, national or international scale, results in both a reduction in step changes in power and reduced times of zero generation, leading to an overall smoothing of the wave-generated electrical power. This has implications for the planning and siting of future wave energy arrays when the industry reaches the point of large-scale deployment.

A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin

NASA Astrophysics Data System (ADS)

Hodell, D.; Lourens, L.; Crowhurst, S.; Konijnendijk, T.; Tjallingii, R.; Jiménez-Espejo, F.; Skinner, L.; Tzedakis, P. C.; Abrantes, Fatima; Acton, Gary D.; Alvarez Zarikian, Carlos A.; Bahr, André; Balestra, Barbara; Barranco, Estefanìa Llave; Carrara, Gabriela; Ducassou, Emmanuelle; Flood, Roger D.; Flores, José-Abel; Furota, Satoshi; Grimalt, Joan; Grunert, Patrick; Hernández-Molina, Javier; Kim, Jin Kyoung; Krissek, Lawrence A.; Kuroda, Junichiro; Li, Baohua; Lofi, Johanna; Margari, Vasiliki; Martrat, Belen; Miller, Madeline D.; Nanayama, Futoshi; Nishida, Naohisa; Richter, Carl; Rodrigues, Teresa; Rodríguez-Tovar, Francisco J.; Roque, Ana Cristina Freixo; Sanchez Goñi, Maria F.; Sierro Sánchez, Francisco J.; Singh, Arun D.; Sloss, Craig R.; Stow, Dorrik A. V.; Takashimizu, Yasuhiro; Tzanova, Alexandrina; Voelker, Antje; Xuan, Chuang; Williams, Trevor

2015-10-01

We produced a composite depth scale and chronology for Site U1385 on the SW Iberian Margin. Using log(Ca/Ti) measured by core scanning XRF at 1-cm resolution in all holes, a composite section was constructed to 166.5 meter composite depth (mcd) that corrects for stretching and squeezing in each core. Oxygen isotopes of benthic foraminifera were correlated to a stacked δ18O reference signal (LR04) to produce an oxygen isotope stratigraphy and age model. Variations in sediment color contain very strong precession signals at Site U1385, and the amplitude modulation of these cycles provides a powerful tool for developing an orbitally-tuned age model. We tuned the U1385 record by correlating peaks in L* to the local summer insolation maxima at 37°N. The benthic δ18O record of Site U1385, when placed on the tuned age model, generally agrees with other time scales within their respective chronologic uncertainties. The age model is transferred to down-core data to produce a continuous time series of log(Ca/Ti) that reflect relative changes of biogenic carbonate and detrital sediment. Biogenic carbonate increases during interglacial and interstadial climate states and decreases during glacial and stadial periods. Much of the variance in the log(Ca/Ti) is explained by a linear combination of orbital frequencies (precession, tilt and eccentricity), whereas the residual signal reflects suborbital climate variability. The strong correlation between suborbital log(Ca/Ti) variability and Greenland temperature over the last glacial cycle at Site U1385 suggests that this signal can be used as a proxy for millennial-scale climate variability over the past 1.5 Ma. Millennial climate variability, as expressed by log(Ca/Ti) at Site U1385, was a persistent feature of glacial climates over the past 1.5 Ma, including glacial periods of the early Pleistocene ('41-kyr world') when boundary conditions differed significantly from those of the late Pleistocene ('100-kyr world'). Suborbital variability was suppressed during interglacial stages and enhanced during glacial periods, especially when benthic δ18O surpassed 3.3-3.5‰. Each glacial inception was marked by appearance of strong millennial variability and each deglaciation was preceded by a terminal stadial event. Suborbital variability may be a symptomatic feature of glacial climate or, alternatively, may play a more active role in the inception and/or termination of glacial cycles.

Toward an Empirically-Based Parametric Explosion Spectral Model

DTIC Science & Technology

2010-09-01

estimated (Richards and Kim, 2009). This archive could potentially provide 200 recordings of explosions at Semipalatinsk Test Site of the former Soviet...estimates of explosion yield, and prior work at the Nevada Test Site (NTS) (e.g., Walter et al., 1995) has found that explosions in weak materials have...2007). Corner frequency scaling of regional seismic phases for underground nuclear explosions at the Nevada Test Site , Bull. Seismol. Soc. Am. 97

Disentangling how landscape spatial and temporal heterogeneity affects Savanna birds.

PubMed

Price, Bronwyn; McAlpine, Clive A; Kutt, Alex S; Ward, Doug; Phinn, Stuart R; Ludwig, John A

2013-01-01

In highly seasonal tropical environments, temporal changes in habitat and resources are a significant determinant of the spatial distribution of species. This study disentangles the effects of spatial and mid to long-term temporal heterogeneity in habitat on the diversity and abundance of savanna birds by testing four competing conceptual models of varying complexity. Focussing on sites in northeast Australia over a 20 year time period, we used ground cover and foliage projected cover surfaces derived from a time series of Landsat Thematic Mapper imagery, rainfall data and site-level vegetation surveys to derive measures of habitat structure at local (1-100 ha) and landscape (100-1000s ha) scales. We used generalised linear models and an information theoretic approach to test the independent effects of spatial and temporal influences on savanna bird diversity and the abundance of eight species with different life-history behaviours. Of four competing models defining influences on assemblages of savanna birds, the most parsimonious included temporal and spatial variability in vegetation cover and site-scale vegetation structure, suggesting savanna bird species respond to spatial and temporal habitat heterogeneity at both the broader landscape scale and at the fine-scale. The relative weight, strength and direction of the explanatory variables changed with each of the eight species, reflecting their different ecology and behavioural traits. This study demonstrates that variations in the spatial pattern of savanna vegetation over periods of 10 to 20 years at the local and landscape scale strongly affect bird diversity and abundance. Thus, it is essential to monitor and manage both spatial and temporal variability in avian habitat to achieve long-term biodiversity outcomes.

Disentangling How Landscape Spatial and Temporal Heterogeneity Affects Savanna Birds

PubMed Central

Price, Bronwyn; McAlpine, Clive A.; Kutt, Alex S.; Ward, Doug; Phinn, Stuart R.; Ludwig, John A.

2013-01-01

In highly seasonal tropical environments, temporal changes in habitat and resources are a significant determinant of the spatial distribution of species. This study disentangles the effects of spatial and mid to long-term temporal heterogeneity in habitat on the diversity and abundance of savanna birds by testing four competing conceptual models of varying complexity. Focussing on sites in northeast Australia over a 20 year time period, we used ground cover and foliage projected cover surfaces derived from a time series of Landsat Thematic Mapper imagery, rainfall data and site-level vegetation surveys to derive measures of habitat structure at local (1–100 ha) and landscape (100–1000s ha) scales. We used generalised linear models and an information theoretic approach to test the independent effects of spatial and temporal influences on savanna bird diversity and the abundance of eight species with different life-history behaviours. Of four competing models defining influences on assemblages of savanna birds, the most parsimonious included temporal and spatial variability in vegetation cover and site-scale vegetation structure, suggesting savanna bird species respond to spatial and temporal habitat heterogeneity at both the broader landscape scale and at the fine-scale. The relative weight, strength and direction of the explanatory variables changed with each of the eight species, reflecting their different ecology and behavioural traits. This study demonstrates that variations in the spatial pattern of savanna vegetation over periods of 10 to 20 years at the local and landscape scale strongly affect bird diversity and abundance. Thus, it is essential to monitor and manage both spatial and temporal variability in avian habitat to achieve long-term biodiversity outcomes. PMID:24066138

Plants and pixels: Comparing phenologies from the ground and from space (Invited)

NASA Astrophysics Data System (ADS)

Rutishauser, T.; Stoekli, R.; Jeanneret, F.; Peñuelas, J.

2010-12-01

Changes in the seasonality of life cycles of plants as recorded in phenological observations have been widely analysed at the species level with data available for many decades back in time. At the same time, seasonality changes in satellite-based observations and prognostic phenology models comprise information at the pixel-size or landscape scale. Change analysis of satellite-based records is restricted due to relatively short satellite records that further include gaps while model-based analyses are biased due to current model deficiencies. At 30 selected sites across Europe, we analysed three different sources of plant seasonality during the 1971-2000 period. Data consisted of (1) species-specific development stages of flowering and leave-out with different species observed at each site. (2) We used a synthetic phenological metric that integrates the common interannual phenological signal across all species at one site. (3) We estimated daily Leaf Area Index with a prognostic phenology model. The prior uncertainties of the model’s empirical parameter space are constrained by assimilating the Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) and Leaf Area Index (LAI) from the MODerate Resolution Imaging Spectroradiometer (MODIS). We extracted the day of year when the 25%, 50% and 75% thresholds were passed each spring. The question arises how the three phenological signals compare and correlate across climate zones in Europe. Is there a match between single species observations, species-based ground-observed metrics and the landscape-scale prognostic model? Are there single key-species across Europe that best represent a landscape scale measure from the prognostic model? Can one source substitute another and serve as proxy-data? What can we learn from potential mismatches? Focusing on changes in spring this contribution presents first results of an ongoing comparison study from a number of European test sites that will be extended to the pan-European phenological database Cost725 and PEP725.

The importance of radiation for semiempirical water-use efficiency models

NASA Astrophysics Data System (ADS)

Boese, Sven; Jung, Martin; Carvalhais, Nuno; Reichstein, Markus

2017-06-01

Water-use efficiency (WUE) is a fundamental property for the coupling of carbon and water cycles in plants and ecosystems. Existing model formulations predicting this variable differ in the type of response of WUE to the atmospheric vapor pressure deficit of water (VPD). We tested a representative WUE model on the ecosystem scale at 110 eddy covariance sites of the FLUXNET initiative by predicting evapotranspiration (ET) based on gross primary productivity (GPP) and VPD. We found that introducing an intercept term in the formulation increases model performance considerably, indicating that an additional factor needs to be considered. We demonstrate that this intercept term varies seasonally and we subsequently associate it with radiation. Replacing the constant intercept term with a linear function of global radiation was found to further improve model predictions of ET. Our new semiempirical ecosystem WUE formulation indicates that, averaged over all sites, this radiation term accounts for up to half (39-47 %) of transpiration. These empirical findings challenge the current understanding of water-use efficiency on the ecosystem scale.

Applications of turbidity monitoring to forest management in California.

PubMed

Harris, Richard R; Sullivan, Kathleen; Cafferata, Peter H; Munn, John R; Faucher, Kevin M

2007-09-01

Many California streams have been adversely affected by sedimentation caused by historic and current land uses, including timber harvesting. The impacts of timber harvesting and logging transportation systems on erosion and sediment delivery can be directly measured, modeled, or inferred from water quality measurements. California regulatory agencies, researchers, and land owners have adopted turbidity monitoring to determine effects of forest management practices on suspended sediment loads and water quality at watershed, project, and site scales. Watershed-scale trends in sediment discharge and responses to current forest practices may be estimated from data collected at automated sampling stations that measure turbidity, stream flow, suspended sediment concentrations, and other water quality parameters. Future results from these studies will provide a basis for assessing the effectiveness of modern forest practice regulations in protecting water quality. At the project scale, manual sampling of water column turbidity during high stream flow events within and downstream from active timber harvest plans can identify emerging sediment sources. Remedial actions can then be taken by managers to prevent or mitigate water quality impacts. At the site scale, manual turbidity sampling during storms or high stream flow events at sites located upstream and downstream from new, upgraded, or decommissioned stream crossings has proven to be a valuable way to determine whether measures taken to prevent post-construction erosion and sediment production are effective. Turbidity monitoring at the project and site scales is therefore an important tool for adaptive management. Uncertainty regarding the effects of current forest practices must be resolved through watershed-scale experiments. In the short term, this uncertainty will stimulate increased use of project and site-scale monitoring.

Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

NASA Astrophysics Data System (ADS)

Hassler, Sibylle; Markus, Weiler; Theresa, Blume

2017-04-01

Transpiration is a key process in the hydrological cycle and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation of hydrological and soil-vegetation-atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls. We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites spread over a 290 km2-catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocities of these 61 trees and determined the importance of the different predictors. Results indicate that a combination of tree-, stand- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, the stand density, geology and aspect. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, are correlated to the temporal dynamics of potential evaporation. Thus, transpiration estimates at the landscape scale would benefit from not only considering hydro-meteorological drivers, but also including tree, stand and site characteristics in order to improve the spatial representation of transpiration for hydrological and soil-vegetation-atmosphere transfer models.

Representativeness of the ground observational sites and up-scaling of the point soil moisture measurements

NASA Astrophysics Data System (ADS)

Chen, Jinlei; Wen, Jun; Tian, Hui

2016-02-01

Soil moisture plays an increasingly important role in the cycle of energy-water exchange, climate change, and hydrologic processes. It is usually measured at a point site, but regional soil moisture is essential for validating remote sensing products and numerical modeling results. In the study reported in this paper, the minimal number of required sites (NRS) for establishing a research observational network and the representative single sites for regional soil moisture estimation are discussed using the soil moisture data derived from the ;Maqu soil moisture observational network; (101°40‧-102°40‧E, 33°30‧-35°45‧N), which is supported by Chinese Academy of Science. Furthermore, the best up-scaling method suitable for this network has been studied by evaluating four commonly used up-scaling methods. The results showed that (1) Under a given accuracy requirement R ⩾ 0.99, RMSD ⩽ 0.02 m3/m3, NRS at both 5 and 10 cm depth is 10. (2) Representativeness of the sites has been validated by time stability analysis (TSA), time sliding correlation analysis (TSCA) and optimal combination of sites (OCS). NST01 is the most representative site at 5 cm depth for the first two methods; NST07 and NST02 are the most representative sites at 10 cm depth. The optimum combination sites at 5 cm depth are NST01, NST02, and NST07. NST05, NST08, and NST13 are the best group at 10 cm depth. (3) Linear fitting, compared with other three methods, is the best up-scaling method for all types of representative sites obtained above, and linear regression equations between a single site and regional soil moisture are established hereafter. ;Single site; obtained by OCS has the greatest up-scaling effect, and TSCA takes the second place. (4) Linear fitting equations show good practicability in estimating the variation of regional soil moisture from July 3, 2013 to July 3, 2014, when a large number of observed soil moisture data are lost.

NREL and IBM Improve Solar Forecasting with Big Data | Energy Systems

Science.gov Websites

forecasting model using deep-machine-learning technology. The multi-scale, multi-model tool, named Watt-sun the first standard suite of metrics for this purpose. Validating Watt-sun at multiple sites across the

Scaling up of Carbon Exchange Dynamics from AmeriFlux Sites to a Super-Region in the Eastern United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hans Peter Schmid; Craig Wayson

The primary objective of this project was to evaluate carbon exchange dynamics across a region of North America between the Great Plains and the East Coast. This region contains about 40 active carbon cycle research (AmeriFlux) sites in a variety of climatic and landuse settings, from upland forest to urban development. The core research involved a scaling strategy that uses measured fluxes of CO{sub 2}, energy, water, and other biophysical and biometric parameters to train and calibrate surface-vegetation-atmosphere models, in conjunction with satellite (MODIS) derived drivers. To achieve matching of measured and modeled fluxes, the ecosystem parameters of the modelsmore » will be adjusted to the dynamically variable flux-tower footprints following Schmid (1997). High-resolution vegetation index variations around the flux sites have been derived from Landsat data for this purpose. The calibrated models are being used in conjunction with MODIS data, atmospheric re-analysis data, and digital land-cover databases to derive ecosystem exchange fluxes over the study domain.« less

Ecosystem Model Performance at Wetlands: Results from the North American Carbon Program Site Synthesis

NASA Astrophysics Data System (ADS)

Sulman, B. N.; Desai, A. R.; Schroeder, N. M.; NACP Site Synthesis Participants

2011-12-01

Northern peatlands contain a significant fraction of the global carbon pool, and their responses to hydrological change are likely to be important factors in future carbon cycle-climate feedbacks. Global-scale carbon cycle modeling studies typically use general ecosystem models with coarse spatial resolution, often without peatland-specific processes. Here, seven ecosystem models were used to simulate CO2 fluxes at three field sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor, sphagnum-dominated bog, from 2002-2006. Flux residuals (simulated - observed) were positively correlated with measured water table for both gross ecosystem productivity (GEP) and ecosystem respiration (ER) at the two fen sites for all models, and were positively correlated with water table at the bog site for the majority of models. Modeled diurnal cycles at fen sites agreed well with eddy covariance measurements overall. Eddy covariance GEP and ER were higher during dry periods than during wet periods, while model results predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP had no significant dependence on water table, while models predicted higher GEP during wet periods. All models significantly over-estimated GEP at the bog site, and all but one over-estimated ER at the bog site. Carbon cycle models in peatland-rich regions could be improved by incorporating better models or measurements of hydrology and by inhibiting GEP and ER rates under saturated conditions. Bogs and fens likely require distinct treatments in ecosystem models due to differences in nutrients, peat properties, and plant communities.

Climatic and agricultural drivers of soil erosion in Africa

NASA Astrophysics Data System (ADS)

Irvine, Brian; Kirkby, Mike; Fleskens, Luuk

2015-04-01

Soil erosion was the most frequently identified driver of land degradation across a selection of global research sites within the DESIRE-EU project. The PESERA model was adopted in the project to upscale field results and consider the potential biophysical impact both with and without stakeholder selected sustainable land management (SLM) technologies in place. The PESERA model was combined with the DESMICE economic model and focussed on forecasting the regional effects of combating desertification both in environmental and socio-economical terms. The PESERA-DESMICE approach is further developed in the WAHARA project to consider the potential of a range of water harvesting technologies to improve biophysical conditions. Modelling in the WAHARA project considers detail of water harvesting technologies at the study site scale through to a coarser application at the continental scale with the latter being informed by the detail provided by study site observations an approach adopted in DESIRE-EU. The PESERA-DESMICE approach considers the difference between a baseline scenario and a (water harvesting) technology scenario at both scales in terms of productivity, financial viability and scope for reducing erosion risk. This paper considers the continental scale and focuses on estimating the impact of in-situ water harvesting technologies across Africa under current and future agricultural and climate pressure. PESERA is adopted in this continental application as it implicitly considers the impact of land-use and climate and can be readily amended to simulate in-situ WHT. Input data for PESERA; land use, management (crop type and planting dates), soil data and topography are derived from global data resources. Climate data for present and future scenarios are available through the QUEST-GSI initiative, where future scenarios are based on the outputs of seven GCM's.

DEVELOPMENT OF REAL-TIME SITE-SPECIFIC MICROSCALE EMISSION FACTOR MODEL FOR THE ASSESSMENT OF HUMAN EXPOSURE TO MOTOR VEHICLE EMISSIONS

EPA Science Inventory

The United States Environmental Protection Agency's (EPA) National Expsoure Research Laboratory (NERL) has initiated a project to improve the methodology for modeling urban-scale human exposure to mobile source emissions. The modeling project has started by considering the nee...

Modeling the Distribution of Migratory Bird Stopovers to Inform Landscape-Scale Siting of Wind Development

PubMed Central

Pocewicz, Amy; Estes-Zumpf, Wendy A.; Andersen, Mark D.; Copeland, Holly E.; Keinath, Douglas A.; Griscom, Hannah R.

2013-01-01

Conservation of migratory birds requires understanding the distribution of and potential threats to their migratory habitats. However, although migratory birds are protected under international treaties, few maps have been available to represent migration at a landscape scale useful to target conservation efforts or inform the siting of wind energy developments that may affect migratory birds. To fill this gap, we developed models that predict where four groups of birds concentrate or stopover during their migration through the state of Wyoming, USA: raptors, wetland, riparian and sparse grassland birds. The models were based on existing literature and expert knowledge concerning bird migration behavior and ecology and validated using expert ratings and known occurrences. There was significant agreement between migratory occurrence data and migration models for all groups except raptors, and all models ranked well with experts. We measured the overlap between the migration concentration models and a predictive model of wind energy development to assess the potential exposure of migratory birds to wind development and illustrate the utility of migratory concentration models for landscape-scale planning. Wind development potential is high across 15% of Wyoming, and 73% of this high potential area intersects important migration concentration areas. From 5.2% to 18.8% of each group’s important migration areas was represented within this high wind potential area, with the highest exposures for sparse grassland birds and the lowest for riparian birds. Our approach could be replicated elsewhere to fill critical data gaps and better inform conservation priorities and landscape-scale planning for migratory birds. PMID:24098379

Stand-level forest structure and avian habitat: Scale dependencies in predicting occurrence in a heterogeneous forest

USGS Publications Warehouse

Smith, K.M.; Keeton, W.S.; Donovan, T.M.; Mitchell, B.

2008-01-01

We explored the role of stand-level forest structure and spatial extent of forest sampling in models of avian occurrence in northern hardwood-conifer forests for two species: black-throated blue warbler (Dendroica caerulescens) and ovenbird (Seiurus aurocapillus). We estimated site occupancy from point counts at 20 sites and characterized the forest structure at these sites at three spatial extents (0.2, 3.0, and 12.0 ha). Weight of evidence was greatest for habitat models using forest stand structure at the 12.0-ha extent and diminished only slightly at the 3.0-ha extent, a scale that was slightly larger than the average territory size of both species. Habitat models characterized at the 0.2-ha extent had low support, yet are the closest in design to those used in many of the habitat studies we reviewed. These results suggest that the role of stand-level vegetation may have been underestimated in the past, which will be of interest to land managers who use habitat models to assess the suitability of habitat for species of concern. Copyright ?? 2008 by the Society of American Foresters.

Scaling in situ cosmogenic nuclide production rates using analytical approximations to atmospheric cosmic-ray fluxes

NASA Astrophysics Data System (ADS)

Lifton, Nathaniel; Sato, Tatsuhiko; Dunai, Tibor J.

2014-01-01

Several models have been proposed for scaling in situ cosmogenic nuclide production rates from the relatively few sites where they have been measured to other sites of interest. Two main types of models are recognized: (1) those based on data from nuclear disintegrations in photographic emulsions combined with various neutron detectors, and (2) those based largely on neutron monitor data. However, stubborn discrepancies between these model types have led to frequent confusion when calculating surface exposure ages from production rates derived from the models. To help resolve these discrepancies and identify the sources of potential biases in each model, we have developed a new scaling model based on analytical approximations to modeled fluxes of the main atmospheric cosmic-ray particles responsible for in situ cosmogenic nuclide production. Both the analytical formulations and the Monte Carlo model fluxes on which they are based agree well with measured atmospheric fluxes of neutrons, protons, and muons, indicating they can serve as a robust estimate of the atmospheric cosmic-ray flux based on first principles. We are also using updated records for quantifying temporal and spatial variability in geomagnetic and solar modulation effects on the fluxes. A key advantage of this new model (herein termed LSD) over previous Monte Carlo models of cosmogenic nuclide production is that it allows for faster estimation of scaling factors based on time-varying geomagnetic and solar inputs. Comparing scaling predictions derived from the LSD model with those of previously published models suggest potential sources of bias in the latter can be largely attributed to two factors: different energy responses of the secondary neutron detectors used in developing the models, and different geomagnetic parameterizations. Given that the LSD model generates flux spectra for each cosmic-ray particle of interest, it is also relatively straightforward to generate nuclide-specific scaling factors based on recently updated neutron and proton excitation functions (probability of nuclide production in a given nuclear reaction as a function of energy) for commonly measured in situ cosmogenic nuclides. Such scaling factors reflect the influence of the energy distribution of the flux folded with the relevant excitation functions. Resulting scaling factors indicate 3He shows the strongest positive deviation from the flux-based scaling, while 14C exhibits a negative deviation. These results are consistent with a recent Monte Carlo-based study using a different cosmic-ray physics code package but the same excitation functions.

Economic decision making and the application of nonparametric prediction models

USGS Publications Warehouse

Attanasi, E.D.; Coburn, T.C.; Freeman, P.A.

2008-01-01

Sustained increases in energy prices have focused attention on gas resources in low-permeability shale or in coals that were previously considered economically marginal. Daily well deliverability is often relatively small, although the estimates of the total volumes of recoverable resources in these settings are often large. Planning and development decisions for extraction of such resources must be areawide because profitable extraction requires optimization of scale economies to minimize costs and reduce risk. For an individual firm, the decision to enter such plays depends on reconnaissance-level estimates of regional recoverable resources and on cost estimates to develop untested areas. This paper shows how simple nonparametric local regression models, used to predict technically recoverable resources at untested sites, can be combined with economic models to compute regional-scale cost functions. The context of the worked example is the Devonian Antrim-shale gas play in the Michigan basin. One finding relates to selection of the resource prediction model to be used with economic models. Models chosen because they can best predict aggregate volume over larger areas (many hundreds of sites) smooth out granularity in the distribution of predicted volumes at individual sites. This loss of detail affects the representation of economic cost functions and may affect economic decisions. Second, because some analysts consider unconventional resources to be ubiquitous, the selection and order of specific drilling sites may, in practice, be determined arbitrarily by extraneous factors. The analysis shows a 15-20% gain in gas volume when these simple models are applied to order drilling prospects strategically rather than to choose drilling locations randomly. Copyright ?? 2008 Society of Petroleum Engineers.

Air Emissions Inventories

EPA Pesticide Factsheets

This site provides access to emissions data, regulations and guidance, electronic system access, resources and tools to support trends analysis, regional, and local scale air quality modeling, regulatory impact assessments.

Capability of a Mobile Monitoring System to Provide Real-Time Data Broadcasting and Near Real-Time Source Attribution

NASA Astrophysics Data System (ADS)

Erickson, M.; Olaguer, J.; Wijesinghe, A.; Colvin, J.; Neish, B.; Williams, J.

2014-12-01

It is becoming increasingly important to understand the emissions and health effects of industrial facilities. Many areas have no or limited sustained monitoring capabilities, making it difficult to quantify the major pollution sources affecting human health, especially in fence line communities. Developments in real-time monitoring and micro-scale modeling offer unique ways to tackle these complex issues. This presentation will demonstrate the capability of coupling real-time observations with micro-scale modeling to provide real-time information and near real-time source attribution. The Houston Advanced Research Center constructed the Mobile Acquisition of Real-time Concentrations (MARC) laboratory. MARC consists of a Ford E-350 passenger van outfitted with a Proton Transfer Reaction Mass Spectrometer (PTR-MS) and meteorological equipment. This allows for the fast measurement of various VOCs important to air quality. The data recorded from the van is uploaded to an off-site database and the information is broadcast to a website in real-time. This provides for off-site monitoring of MARC's observations, which allows off-site personnel to provide immediate input to the MARC operators on how to best achieve project objectives. The information stored in the database can also be used to provide near real-time source attribution. An inverse model has been used to ascertain the amount, location, and timing of emissions based on MARC measurements in the vicinity of industrial sites. The inverse model is based on a 3D micro-scale Eulerian forward and adjoint air quality model known as the HARC model. The HARC model uses output from the Quick Urban and Industrial Complex (QUIC) wind model and requires a 3D digital model of the monitored facility based on lidar or industrial permit data. MARC is one of the instrument platforms deployed during the 2014 Benzene and other Toxics Exposure Study (BEE-TEX) in Houston, TX. The main goal of the study is to quantify and explain the origin of ambient exposure to hazardous air pollutants in an industrial fence line community near the Houston Ship Channel. Preliminary results derived from analysis of MARC observations during the BEE-TEX experiment will be presented.

Predicting the natural flow regime: Models for assessing hydrological alteration in streams

USGS Publications Warehouse

Carlisle, D.M.; Falcone, J.; Wolock, D.M.; Meador, M.R.; Norris, R.H.

2009-01-01

Understanding the extent to which natural streamflow characteristics have been altered is an important consideration for ecological assessments of streams. Assessing hydrologic condition requires that we quantify the attributes of the flow regime that would be expected in the absence of anthropogenic modifications. The objective of this study was to evaluate whether selected streamflow characteristics could be predicted at regional and national scales using geospatial data. Long-term, gaged river basins distributed throughout the contiguous US that had streamflow characteristics representing least disturbed or near pristine conditions were identified. Thirteen metrics of the magnitude, frequency, duration, timing and rate of change of streamflow were calculated using a 20-50 year period of record for each site. We used random forests (RF), a robust statistical modelling approach, to develop models that predicted the value for each streamflow metric using natural watershed characteristics. We compared the performance (i.e. bias and precision) of national- and regional-scale predictive models to that of models based on landscape classifications, including major river basins, ecoregions and hydrologic landscape regions (HLR). For all hydrologic metrics, landscape stratification models produced estimates that were less biased and more precise than a null model that accounted for no natural variability. Predictive models at the national and regional scale performed equally well, and substantially improved predictions of all hydrologic metrics relative to landscape stratification models. Prediction error rates ranged from 15 to 40%, but were 25% for most metrics. We selected three gaged, non-reference sites to illustrate how predictive models could be used to assess hydrologic condition. These examples show how the models accurately estimate predisturbance conditions and are sensitive to changes in streamflow variability associated with long-term land-use change. We also demonstrate how the models can be applied to predict expected natural flow characteristics at ungaged sites. ?? 2009 John Wiley & Sons, Ltd.

Case studies, cross-site comparisons, and the challenge of generalization: comparing agent-based models of land-use change in frontier regions

PubMed Central

Parker, Dawn C.; Entwisle, Barbara; Rindfuss, Ronald R.; Vanwey, Leah K.; Manson, Steven M.; Moran, Emilio; An, Li; Deadman, Peter; Evans, Tom P.; Linderman, Marc; Rizi, S. Mohammad Mussavi; Malanson, George

2009-01-01

Cross-site comparisons of case studies have been identified as an important priority by the land-use science community. From an empirical perspective, such comparisons potentially allow generalizations that may contribute to production of global-scale land-use and land-cover change projections. From a theoretical perspective, such comparisons can inform development of a theory of land-use science by identifying potential hypotheses and supporting or refuting evidence. This paper undertakes a structured comparison of four case studies of land-use change in frontier regions that follow an agent-based modeling approach. Our hypothesis is that each case study represents a particular manifestation of a common process. Given differences in initial conditions among sites and the time at which the process is observed, actual mechanisms and outcomes are anticipated to differ substantially between sites. Our goal is to reveal both commonalities and differences among research sites, model implementations, and ultimately, conclusions derived from the modeling process. PMID:19960107

Case studies, cross-site comparisons, and the challenge of generalization: comparing agent-based models of land-use change in frontier regions.

PubMed

Parker, Dawn C; Entwisle, Barbara; Rindfuss, Ronald R; Vanwey, Leah K; Manson, Steven M; Moran, Emilio; An, Li; Deadman, Peter; Evans, Tom P; Linderman, Marc; Rizi, S Mohammad Mussavi; Malanson, George

2008-01-01

Cross-site comparisons of case studies have been identified as an important priority by the land-use science community. From an empirical perspective, such comparisons potentially allow generalizations that may contribute to production of global-scale land-use and land-cover change projections. From a theoretical perspective, such comparisons can inform development of a theory of land-use science by identifying potential hypotheses and supporting or refuting evidence. This paper undertakes a structured comparison of four case studies of land-use change in frontier regions that follow an agent-based modeling approach. Our hypothesis is that each case study represents a particular manifestation of a common process. Given differences in initial conditions among sites and the time at which the process is observed, actual mechanisms and outcomes are anticipated to differ substantially between sites. Our goal is to reveal both commonalities and differences among research sites, model implementations, and ultimately, conclusions derived from the modeling process.

From Dynamic Global Vegetation Modelling to Real-World regional and local Application

NASA Astrophysics Data System (ADS)

Steinkamp, J.; Forrest, M.; Kamm, K.; Leiblein-Wild, M.; Pachzelt, A.; Werner, C.; Hickler, T.

2015-12-01

Dynamic (global) vegetation models (DGVM) can be applied to any spatial resolution on the local, national, continental and global scale given suitable climatic and geographic input forcing data. LPJ-GUESS, the main DGVM applied in our research group, uses the plant functional type (PFT) concept in the global setup with typically about 10-20 tree PFTs (subdivided into tropical, temperate and boreal) and two herbaceous PFTs by default. When modelling smaller spatial extents, such as continental (e.g. Europe/North America) national domains, or individual sites (e.g. Frankfurt, Germany), i.e. the scale of decision making, it becomes necessary to refine the PFT representation, the model initialization and validation and, in some case, to include additional processes. I will present examples of LPJ-GUESS applications at the continental to local scale performed by our working group including i.) a European simulation representing the main tree species and Mediterranean shrubs, ii.) a climate impact study for Turkey, iii.) coupled dynamic large grazer-vegetation modelling across Africa and, iv.) modelling an allergenic and in Europe invasive shrub (Ambrosia artemisiifolia), iv.) simulating water usage by an oak-pine forest stand near Frankfurt, and v.) stand specific differences in modelling at the FACE sites. Finally, I will present some thoughts on how to advance the models in terms of more detailed and realistic PFT or species parameterizations accounting for adaptive functional trait responses also within species.

Field-Integrated Studies of Long-Term Sustainability of Chromium Bioreduction at Hanford 100H Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Philip E.

2006-06-01

The objectives of the project are to investigate coupled hydraulic, geochemical, and microbial conditions, and to determine the critical biogeochemical parameters necessary to maximize the extent of Cr(VI) bioreduction and minimize Cr(III) reoxidation in groundwater. Specific goals of the project are as follows: (1) Field testing and monitoring of Cr(VI) bioreduction in ground water and its transformation into insoluble species of Cr(III) at the Hanford 100H site, to develop the optimal strategy of water sampling for chemical, microbial, stable isotope analyses, and noninvasive geophysical monitoring; (2) Bench-scale flow and transport investigations using columns of undisturbed sediments to obtain diffusion andmore » kinetic parameters needed for the development of a numerical model, predictions of Cr(VI) bioreduction, and potential of Cr(III) reoxidation; and (3) Development of a multiphase, multi-component 3D reactive transport model and a code, TOUGHREACT-BIO, to predict coupled biogeochemical-hydrological processes associated with bioremediation, and to calibrate and validate the developed code based on the results of bench-scale and field-scale Cr(VI) biostimulation experiments in ground water at the Hanford Site.« less

Multimethod, multistate Bayesian hierarchical modeling approach for use in regional monitoring of wolves.

PubMed

Jiménez, José; García, Emilio J; Llaneza, Luis; Palacios, Vicente; González, Luis Mariano; García-Domínguez, Francisco; Múñoz-Igualada, Jaime; López-Bao, José Vicente

2016-08-01

In many cases, the first step in large-carnivore management is to obtain objective, reliable, and cost-effective estimates of population parameters through procedures that are reproducible over time. However, monitoring predators over large areas is difficult, and the data have a high level of uncertainty. We devised a practical multimethod and multistate modeling approach based on Bayesian hierarchical-site-occupancy models that combined multiple survey methods to estimate different population states for use in monitoring large predators at a regional scale. We used wolves (Canis lupus) as our model species and generated reliable estimates of the number of sites with wolf reproduction (presence of pups). We used 2 wolf data sets from Spain (Western Galicia in 2013 and Asturias in 2004) to test the approach. Based on howling surveys, the naïve estimation (i.e., estimate based only on observations) of the number of sites with reproduction was 9 and 25 sites in Western Galicia and Asturias, respectively. Our model showed 33.4 (SD 9.6) and 34.4 (3.9) sites with wolf reproduction, respectively. The number of occupied sites with wolf reproduction was 0.67 (SD 0.19) and 0.76 (0.11), respectively. This approach can be used to design more cost-effective monitoring programs (i.e., to define the sampling effort needed per site). Our approach should inspire well-coordinated surveys across multiple administrative borders and populations and lead to improved decision making for management of large carnivores on a landscape level. The use of this Bayesian framework provides a simple way to visualize the degree of uncertainty around population-parameter estimates and thus provides managers and stakeholders an intuitive approach to interpreting monitoring results. Our approach can be widely applied to large spatial scales in wildlife monitoring where detection probabilities differ between population states and where several methods are being used to estimate different population parameters. © 2016 Society for Conservation Biology.

Soil carbon storage following road removal and timber harvesting in redwood forests

USGS Publications Warehouse

Seney, Joseph; Madej, Mary Ann

2015-01-01

Soil carbon storage plays a key role in the global carbon cycle and is important for sustaining forest productivity. Removal of unpaved forest roads has the potential for increasing carbon storage in soils on forested terrain as treated sites revegetate and soil properties improve on the previously compacted road surfaces. We compared soil organic carbon (SOC) content at several depths on treated roads to SOC in adjacent second-growth forests and old-growth redwood forests in California, determined whether SOC in the upper 50 cm of soil varies with the type of road treatment, and assessed the relative importance of site-scale and landscape-scale variables in predicting SOC accumulation in treated road prisms and second-growth redwood forests. Soils were sampled at 5, 20, and 50 cm depths on roads treated by two methods (decommissioning and full recontouring), and in adjacent second-growth and old-growth forests in north coastal California. Road treatments spanned a period of 32 years, and covered a range of geomorphic and vegetative conditions. SOC decreased with depth at all sites. Treated roads on convex sites exhibited higher SOC than on concave sites, and north aspect sites had higher SOC than south aspect sites. SOC at 5, 20, and 50 cm depths did not differ significantly between decommissioned roads (treated 18–32 years previous) and fully recontoured roads (treated 2–12 years previous). Nevertheless, stepwise multiple regression models project higher SOC developing on fully recontoured roads in the next few decades. The best predictors for SOC on treated roads and in second-growth forest incorporated aspect, vegetation type, soil depth, lithology, distance from the ocean, years since road treatment (for the road model) and years since harvest (for the forest model). The road model explained 48% of the variation in SOC in the upper 50 cm of mineral soils and the forest model, 54%

Psychosocial development of full term singletons, born after preimplantation genetic diagnosis (PGD) at preschool age and family functioning: a prospective case-controlled study and multi-informant approach.

PubMed

Winter, C; Van Acker, F; Bonduelle, M; Desmyttere, S; Nekkebroeck, J

2015-05-01

Do full term singletons born after preimplantation genetic diagnosis (PGD) differ in their psychosocial functioning from children born after intracytoplasmic sperm injection (ICSI) and spontaneous conceived controls (SC)? The psychosocial maturation process of 5-6-year-old PGD children is comparable between the three conception groups (PGD, ICSI and SC). In general, a lot of research has been published regarding follow-up of children born after artificial reproductive technologies (ART), which mainly is reassuring. But the ART population itself is marked by broad diversity [IVF, ICSI, gamete donation, preimplantation genetic screening (PGS) or PGD] which complicates comparisons. Some literature concerning the socio-emotional development of PGD/PGS children is available and it suggests a normal maturation process. However, the complex reality of PGD families (e.g. safety of the technique and psychological burden of genetic histories) asks for an exclusive PGD sample with matched control groups and a multi-informant approach. Between April 2011 and May 2013, the psychosocial wellbeing of preschoolers and their families born after PGD was assessed in a prospective case-controlled, matched follow-up study, with a multi-informant approach. A group of 47 PGD, 50 ICSI and 55 SC 5-6-year-old children participated in a follow-up study performed at the Centre for Medical Genetics of the Universitair Ziekenhuis Brussel (UZ Brussel). Assessments took place in the hospital and in kindergartens. Children performed the Bene-Anthony family relations test (FRT), yielding their perceptions upon family relationships. Parents and teachers completed the child behaviour checklist (CBCL) and Caregiver Teacher Report Form (C-/TRF), respectively. Parental and family functioning were measured by the NEO-FFi, the parenting stress index (PSI), the Greenberger Work-Parenting Investment Questionnaire and the Marlowe-Crowne Social Desirability Scale (MCSDS). Statistical analysis was performed by using analysis of covariance (ANCOVA). No differences were detected between the psychosocial development of PGD children and the control groups. Parents did not differ in reporting problem behaviour and they were stricter than teachers. Concerning family functioning the ART parents scored comparable with each other. PGD and ICSI mothers were emotionally more stable [NEO-FFi Neuroticism/emotionality: P = 0.013, η(2) = 0.066; 95% confidence interval (CI) 95% (0.003;0.148)]. They experienced less parental stress in general [PSI, Total stress: P = 0.001, η(2) = 0.102, 95% CI (0.02;0.192)] and on different sublevels opposed to their SC counterparts. Yet ART mothers presented higher ratings on the NEO-FFi Conscientiousness [P = 0.011, η(2) = 0.064; 95% CI (0.003;0.144)] indicating a higher feeling of competence and goal directedness. Mediation analysis confirmed: PGD and ICSI mothers who experienced less family stress were emotionally more stable. A power analysis indicated that a sample with 152 children is sufficient to detect a medium size effect with 80% power using ANCOVA. The current sample comprised only Dutch speaking Caucasians, hence conclusions should be drawn cautiously. Future research should include larger groups, prematures, multiples and children from different cultural backgrounds. This current research is the first to compare PGD preschoolers with matched controls. Concerns about the behavioural effects on the offspring should not inhibit the use of PGD. Furthermore, our findings suggest that on the long run ART procedures might enhance personal resources of women to cope with family stress. These findings are reassuring for women who might feel insecure and anxious during their ART trajectory. This research project gained funding from the OZR (a grant by the Research group of the Vrije Universiteit Brussel), the FWO (Fonds Wetenschappelijk Onderzoek) and the Wetenschappelijk Fonds Willy Gepts. The UZ Brussel and the Centre of Medical Genetics received funding from pharmaceutical firms for data collection. UZ Brussel and the Centre for Medical Genetics have received many educational grants for organizing the data collection, from IBSA, Ferring, Organon, Shering-Plough, Merck and Merck Belgium. M.B. has received consultancy and speaker's fees from Organon, Serono Symposia and Merck. The other authors have no competing interests. not applicable. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Full-scale monitoring of wind and suspension bridge response

NASA Astrophysics Data System (ADS)

Snæbjörnsson, J. T.; Jakobsen, J. B.; Cheynet, E.; Wang, J.

2017-12-01

Monitoring of real structures is important for many reasons. For structures susceptible to environmental actions, full-scale observations can provide valuable information about the environmental conditions at the site, as well as the characteristics of the excitation acting on the structure. The recorded data, if properly analyzed, can be used to validate and/or update experiments and models used in the design of new structures, such as the load description and modelling of the structural response. Various aspects of full-scale monitoring are discussed in the paper and the full-scale wind engineering laboratory at the Lysefjord suspension bridge introduced. The natural excitation of the bridge comes from wind and traffic. The surrounding terrain is complex and its effect on the wind flow can only be fully studied on site, in full-scale. The monitoring program and associated data analysis are described. These include various studies of the relevant turbulence characteristics, identification of dynamic properties and estimation of wind- and traffic-induced response parameters. The overall monitoring activity also included a novel application of the remote optical sensing in bridge engineering, which is found to have an important potential to complement traditional “single-point” wind observations by sonic anemometers.

Mapping spatial patterns of denitrifiers at large scales (Invited)

NASA Astrophysics Data System (ADS)

Philippot, L.; Ramette, A.; Saby, N.; Bru, D.; Dequiedt, S.; Ranjard, L.; Jolivet, C.; Arrouays, D.

2010-12-01

Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. Here we combined molecular approaches and geostatistical modeling to explore spatial patterns of the denitrifying community at large scales. The distribution of denitrifrying community was investigated over 107 sites in Burgundy, a 31 500 km2 region of France, using a 16 X 16 km sampling grid. At each sampling site, the abundances of denitrifiers and 42 soil physico-chemical properties were measured. The relative contributions of land use, spatial distance, climatic conditions, time and soil physico-chemical properties to the denitrifier spatial distribution were analyzed by canonical variation partitioning. Our results indicate that 43% to 85% of the spatial variation in community abundances could be explained by the measured environmental parameters, with soil chemical properties (mostly pH) being the main driver. We found spatial autocorrelation up to 739 km and used geostatistical modelling to generate predictive maps of the distribution of denitrifiers at the landscape scale. Studying the distribution of the denitrifiers at large scale can help closing the artificial gap between the investigation of microbial processes and microbial community ecology, therefore facilitating our understanding of the relationships between the ecology of denitrifiers and N-fluxes by denitrification.

Scaling Forest Management Practices in Earth System Models: Case Study of Southeast and Pacific Northwest Forests

NASA Astrophysics Data System (ADS)

Pourmokhtarian, A.; Becknell, J. M.; Hall, J.; Desai, A. R.; Boring, L. R.; Duffy, P.; Staudhammer, C. L.; Starr, G.; Dietze, M.

2014-12-01

A wide array of human-induced disturbances can alter the structure and function of forests, including climate change, disturbance and management. While there have been numerous studies on climate change impacts on forests, interactions of management with changing climate and natural disturbance are poorly studied. Forecasts of the range of plausible responses of forests to climate change and management are need for informed decision making on new management approaches under changing climate, as well as adaptation strategies for coming decades. Terrestrial biosphere models (TBMs) provide an excellent opportunity to investigate and assess simultaneous responses of terrestrial ecosystems to climatic perturbations and management across multiple spatio-temporal scales, but currently do not represent a wide array of management activities known to impact carbon, water, surface energy fluxes, and biodiversity. The Ecosystem Demography model 2 (ED2) incorporates non-linear impacts of fine-scale (~10-1 km) heterogeneity in ecosystem structure both horizontally and vertically at a plant level. Therefore it is an ideal candidate to incorporate different forest management practices and test various hypotheses under changing climate and across various spatial scales. The management practices that we implemented were: clear-cut, conversion, planting, partial harvest, low intensity fire, restoration, salvage, and herbicide. The results were validated against observed data across 8 different sites in the U.S. Southeast (Duke Forest, Joseph Jones Ecological Research Center, North Carolina Loblolly Pine, and Ordway-Swisher Biological Station) and Pacific Northwest (Metolius Research Natural Area, H.J. Andrews Experimental Forest, Wind River Field Station, and Mount Rainier National Park). These sites differ in regards to climate, vegetation, soil, and historical land disturbance as well as management approaches. Results showed that different management practices could successfully and realistically be implemented in the ED2 model at a site level. Moreover, sensitivity analyses determined the most important processes at different spatial scales, and also those which could be ignored while minimizing overall error.

Climate insensitivity of treeline in the Canadian Rocky Mountains

NASA Astrophysics Data System (ADS)

Johnson, E. A.; Macias Fauria, M.

2011-12-01

Successful modelling efforts demonstrate that tree presence over a ~ 200 km2 alpine/subalpine area in the Front Ranges of the Canadian Rocky Mountains results from a multi-scale spatiotemporal process competition involving not only growing season temperatures but also topographical shelter, water availability, and substrate stability and availability. The study area was selected to represent the diversity of substrates and geomorphologic processes found in the Canadian Rockies, and ranges in elevation from 1400 to > 2800 meters above sea level. Tree presence was mapped at 10m resolution using a combination of remote sensing imagery (taken in 2008) and intensive ground truthing, and modelled with an ensemble of state-of-the-art environmental envelope models. Explanatory variables chosen represented not only temperature and moisture availability (computed over 1971-2000 climate normals), but also substrate diversity, slope angle and type, geomorphologic features, modelled regolith depth, and concavity/convexity of the terrain. Such variables were meant to serve as proxies for known convergent and divergent processes that occur on steep landscapes and that have profound influence on tree establishment and survival. Model performance was very high and revealed substrate and geomorphology to be the most important explanatory variables for tree presence in the area. Available high-resolution imagery for 1954 enabled the mapping of tree presence over most of the study area and the identification of changes in the distribution of trees over the last nearly six decades. Overall, the only major observed changes were related to post-fire stand recovery, and areas with treeline advance were insignificant at the landscape scale. Tree suitable sites were projected onto high resolution grids of late 21st century climatic conditions predicted by regional climate models driven by atmosphere-ocean general circulation models. Emissions scenario was A2 (as defined in the Special Report on Emissions Scenarios used by the Intergovernmental Panel on Climate Change), at the higher end of emissions scenarios, and thus at the higher end of forecasted temperature increases. Projected changes in tree site availability were minimal at the landscape scale, as the presence of trees in the uppermost part of these forests largely depends on the existence of suitable sites largely linked to topography. Such places are the result of geomorphologic processes acting on a framework set by the structural geology of the region, and thus the appearance of new sites suitable for tree growth does not depend on short (i.e. yearly to decadal) time scales but on longer ones (i.e. centuries to millennia). This work has the strength of studying treeline over a whole area, thus avoiding potential biases in the regional representativity of local study sites, and warns against careless upscaling of site-based studies. Moreover, we suggest that the term 'treeline' is weak at a high-resolution landscape scale in our study area (i.e. young glaciated terrain) because the distribution of trees over the landscape is spatially irregular and most of the processes enabling or preventing tree presence occur over its whole elevational range.

Meter scale variation in shrub dominance and soil moisture structure Arctic arthropod communities

PubMed Central

Hansen, Oskar Liset Pryds; Bowden, Joseph J.; Treier, Urs A.; Normand, Signe; Høye, Toke

2016-01-01

The Arctic is warming at twice the rate of the rest of the world. This impacts Arctic species both directly, through increased temperatures, and indirectly, through structural changes in their habitats. Species are expected to exhibit idiosyncratic responses to structural change, which calls for detailed investigations at the species and community level. Here, we investigate how arthropod assemblages of spiders and beetles respond to variation in habitat structure at small spatial scales. We sampled transitions in shrub dominance and soil moisture between three different habitats (fen, dwarf shrub heath, and tall shrub tundra) at three different sites along a fjord gradient in southwest Greenland, using yellow pitfall cups. We identified 2,547 individuals belonging to 47 species. We used species richness estimation, indicator species analysis and latent variable modeling to examine differences in arthropod community structure in response to habitat variation at local (within site) and regional scales (between sites). We estimated species responses to the environment by fitting species-specific generalized linear models with environmental covariates. Species assemblages were segregated at the habitat and site level. Each habitat hosted significant indicator species, and species richness and diversity were significantly lower in fen habitats. Assemblage patterns were significantly linked to changes in soil moisture and vegetation height, as well as geographic location. We show that meter-scale variation among habitats affects arthropod community structure, supporting the notion that the Arctic tundra is a heterogeneous environment. To gain sufficient insight into temporal biodiversity change, we require studies of species distributions detailing species habitat preferences. PMID:27478709

The $500 Million Question: Can Charter Management Organizations Deliver Quality Education at Scale?

ERIC Educational Resources Information Center

Hall, Kevin; Lake, Robin

2011-01-01

Charter school management organizations (CMOs) have emerged as a popular means for bringing charter schooling to scale. Advocates credit CMOs with delivering a coherent model of charter schooling to a growing number of children across numerous sites. Skeptics have wondered whether CMOs constitute an effective management approach, whether they…

Comparing estimates of population change from occupancy and mark-recapture models for a territorial species

Treesearch

Mary M. Conner; John J. Keane; Claire V. Gallagher; Thomas E. Munton; Paula A. Shaklee

2016-01-01

Monitoring studies often use marked animals to estimate population abundance at small spatial scales. However, at smaller scales, occupancy sampling, which uses detection/nondetection data, may be useful where sites are approximately territories, and occupancy dynamics should be strongly correlated with population dynamics. Occupancy monitoring has advantages...

When small changes matter: the role of cross-scale interactions between habitat and ecological connectivity in recovery.

PubMed

Thrush, Simon F; Hewitt, Judi E; Lohrer, Andrew M; Chiaroni, Luca D

2013-01-01

Interaction between the diversity of local communities and the degree of connectivity between them has the potential to influence local recovery rates and thus profoundly affect community dynamics in the face of the cumulative impacts that occur across regions. Although such complex interactions have been modeled, field experiments in natural ecosystems to investigate the importance of interactions between local and regional processes are rare, especially so in coastal marine seafloor habitats subjected to many types of disturbance. We conducted a defaunation experiment at eight subtidal sites, incorporating manipulation of habitat structure, to test the relative importance of local habitat features and colonist supply in influencing macrobenthic community recovery rate. Our sites varied in community composition, habitat characteristics, and hydrodynamic conditions, and we conducted the experiment in two phases, exposing defaunated plots to colonists during periods of either high or low larval colonist supply. In both phases of the experiment, five months after disturbance, we were able to develop models that explained a large proportion of variation in community recovery rate between sites. Our results emphasize that the connectivity to the regional species pool influences recovery rate, and although local habitat effects were important, the strength of these effects was affected by broader-scale site characteristics and connectivity. Empirical evidence that cross-scale interactions are important in disturbance-recovery dynamics emphasizes the complex dynamics underlying seafloor community responses to cumulative disturbance.

Generalizing ecological site concepts of the Colorado Plateau for landscape-level applications

USGS Publications Warehouse

Duniway, Michael C.; Nauman, Travis; Johanson, Jamin K.; Green, Shane; Miller, Mark E.; Bestelmeyer, Brandon T.

2016-01-01

Numerous ecological site descriptions in the southern Utah portion of the Colorado Plateau can be difficult to navigate, so we held a workshop aimed at adding value and functionality to the current ecological site system.We created new groups of ecological sites and drafted state-and-transition models for these new groups.We were able to distill the current large number of ecological sites in the study area (ca. 150) into eight ecological site groups that capture important variability in ecosystem dynamics.Several inventory and monitoring programs and landscape scale planning actions will likely benefit from more generalized ecological site group concepts.

Prediction of resource volumes at untested locations using simple local prediction models

USGS Publications Warehouse

Attanasi, E.D.; Coburn, T.C.; Freeman, P.A.

2006-01-01

This paper shows how local spatial nonparametric prediction models can be applied to estimate volumes of recoverable gas resources at individual undrilled sites, at multiple sites on a regional scale, and to compute confidence bounds for regional volumes based on the distribution of those estimates. An approach that combines cross-validation, the jackknife, and bootstrap procedures is used to accomplish this task. Simulation experiments show that cross-validation can be applied beneficially to select an appropriate prediction model. The cross-validation procedure worked well for a wide range of different states of nature and levels of information. Jackknife procedures are used to compute individual prediction estimation errors at undrilled locations. The jackknife replicates also are used with a bootstrap resampling procedure to compute confidence bounds for the total volume. The method was applied to data (partitioned into a training set and target set) from the Devonian Antrim Shale continuous-type gas play in the Michigan Basin in Otsego County, Michigan. The analysis showed that the model estimate of total recoverable volumes at prediction sites is within 4 percent of the total observed volume. The model predictions also provide frequency distributions of the cell volumes at the production unit scale. Such distributions are the basis for subsequent economic analyses. ?? Springer Science+Business Media, LLC 2007.

Large-scale Estimates of Leaf Area Index from Active Remote Sensing Laser Altimetry

NASA Astrophysics Data System (ADS)

Hopkinson, C.; Mahoney, C.

2016-12-01

Leaf area index (LAI) is a key parameter that describes the spatial distribution of foliage within forest canopies which in turn control numerous relationships between the ground, canopy, and atmosphere. The retrieval of LAI has demonstrated success by in-situ (digital) hemispherical photography (DHP) and airborne laser scanning (ALS) data; however, field and ALS acquisitions are often spatially limited (100's km2) and costly. Large-scale (>1000's km2) retrievals have been demonstrated by optical sensors, however, accuracies remain uncertain due to the sensor's inability to penetrate the canopy. The spaceborne Geoscience Laser Altimeter System (GLAS) provides a possible solution in retrieving large-scale derivations whilst simultaneously penetrating the canopy. LAI retrieved by multiple DHP from 6 Australian sites, representing a cross-section of Australian ecosystems, were employed to model ALS LAI, which in turn were used to infer LAI from GLAS data at 5 other sites. An optimally filtered GLAS dataset was then employed in conjunction with a host of supplementary data to build a Random Forest (RF) model to infer predictions (and uncertainties) of LAI at a 250 m resolution across the forested regions of Australia. Predictions were validated against ALS-based LAI from 20 sites (R2=0.64, RMSE=1.1 m2m-2); MODIS-based LAI were also assessed against these sites (R2=0.30, RMSE=1.78 m2m-2) to demonstrate the strength of GLAS-based predictions. The large-scale nature of current predictions was also leveraged to demonstrate large-scale relationships of LAI with other environmental characteristics, such as: canopy height, elevation, and slope. The need for such wide-scale quantification of LAI is key in the assessment and modification of forest management strategies across Australia. Such work also assists Australia's Terrestrial Ecosystem Research Network, in fulfilling their government issued mandates.

Fine-temporal forecasting of outbreak probability and severity: Ross River virus in Western Australia.

PubMed

Koolhof, I S; Bettiol, S; Carver, S

2017-10-01

Health warnings of mosquito-borne disease risk require forecasts that are accurate at fine-temporal resolutions (weekly scales); however, most forecasting is coarse (monthly). We use environmental and Ross River virus (RRV) surveillance to predict weekly outbreak probabilities and incidence spanning tropical, semi-arid, and Mediterranean regions of Western Australia (1991-2014). Hurdle and linear models were used to predict outbreak probabilities and incidence respectively, using time-lagged environmental variables. Forecast accuracy was assessed by model fit and cross-validation. Residual RRV notification data were also examined against mitigation expenditure for one site, Mandurah 2007-2014. Models were predictive of RRV activity, except at one site (Capel). Minimum temperature was an important predictor of RRV outbreaks and incidence at all predicted sites. Precipitation was more likely to cause outbreaks and greater incidence among tropical and semi-arid sites. While variable, mitigation expenditure coincided positively with increased RRV incidence (r 2 = 0·21). Our research demonstrates capacity to accurately predict mosquito-borne disease outbreaks and incidence at fine-temporal resolutions. We apply our findings, developing a user-friendly tool enabling managers to easily adopt this research to forecast region-specific RRV outbreaks and incidence. Approaches here may be of value to fine-scale forecasting of RRV in other areas of Australia, and other mosquito-borne diseases.

Microbiological-enhanced mixing across scales during in-situ bioreduction of metals and radionuclides at Department of Energy Sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valocchi, Albert; Werth, Charles; Liu, Wen-Tso

Bioreduction is being actively investigated as an effective strategy for subsurface remediation and long-term management of DOE sites contaminated by metals and radionuclides (i.e. U(VI)). These strategies require manipulation of the subsurface, usually through injection of chemicals (e.g., electron donor) which mix at varying scales with the contaminant to stimulate metal reducing bacteria. There is evidence from DOE field experiments suggesting that mixing limitations of substrates at all scales may affect biological growth and activity for U(VI) reduction. Although current conceptual models hold that biomass growth and reduction activity is limited by physical mixing processes, a growing body of literaturemore » suggests that reaction could be enhanced by cell-to-cell interaction occurring over length scales extending tens to thousands of microns. Our project investigated two potential mechanisms of enhanced electron transfer. The first is the formation of single- or multiple-species biofilms that transport electrons via direct electrical connection such as conductive pili (i.e. ‘nanowires’) through biofilms to where the electron acceptor is available. The second is through diffusion of electron carriers from syntrophic bacteria to dissimilatory metal reducing bacteria (DMRB). The specific objectives of this work are (i) to quantify the extent and rate that electrons are transported between microorganisms in physical mixing zones between an electron donor and electron acceptor (e.g. U(IV)), (ii) to quantify the extent that biomass growth and reaction are enhanced by interspecies electron transport, and (iii) to integrate mixing across scales (e.g., microscopic scale of electron transfer and macroscopic scale of diffusion) in an integrated numerical model to quantify these mechanisms on overall U(VI) reduction rates. We tested these hypotheses with five tasks that integrate microbiological experiments, unique micro-fluidics experiments, flow cell experiments, and multi-scale numerical models. Continuous fed-batch reactors were used to derive kinetic parameters for DMRB, and to develop an enrichment culture for elucidation of syntrophic relationships in a complex microbial community. Pore and continuum scale experiments using microfluidic and bench top flow cells were used to evaluate the impact of cell-to-cell and microbial interactions on reaction enhancement in mixing-limited bioactive zones, and the mechanisms of this interaction. Some of the microfluidic experiments were used to develop and test models that considers direct cell-to-cell interactions during metal reduction. Pore scale models were incorporated into a multi-scale hybrid modeling framework that combines pore scale modeling at the reaction interface with continuum scale modeling. New computational frameworks for combining continuum and pore-scale models were also developed« less

System-Scale Model of Aquifer, Vadose Zone, and River Interactions for the Hanford 300 Area - Application to Uranium Reactive Transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rockhold, Mark L.; Bacon, Diana H.; Freedman, Vicky L.

2013-10-01

This report represents a synthesis and integration of basic and applied research into a system-scale model of the Hanford 300 Area groundwater uranium plume, supported by the U.S. Department of Energy’s Richland Operations (DOE-RL) office. The report integrates research findings and data from DOE Office of Science (DOE-SC), Office of Environmental Management (DOE-EM), and DOE-RL projects, and from the site remediation and closure contractor, Washington Closure Hanford, LLC (WCH). The three-dimensional, system-scale model addresses water flow and reactive transport of uranium for the coupled vadose zone, unconfined aquifer, and Columbia River shoreline of the Hanford 300 Area. The system-scale modelmore » of the 300 Area was developed to be a decision-support tool to evaluate processes of the total system affecting the groundwater uranium plume. The model can also be used to address “what if” questions regarding different remediation endpoints, and to assist in design and evaluation of field remediation efforts. For example, the proposed cleanup plan for the Hanford 300 Area includes removal, treatment, and disposal of contaminated sediments from known waste sites, enhanced attenuation of uranium hot spots in the vadose and periodically rewetted zone, and continued monitoring of groundwater with institutional controls. Illustrative simulations of polyphosphate infiltration were performed to demonstrate the ability of the system-scale model to address these types of questions. The use of this model in conjunction with continued field monitoring is expected to provide a rigorous basis for developing operational strategies for field remediation and for defining defensible remediation endpoints.« less

Impact of Aquifer Heterogeneities on Autotrophic Denitrification.

NASA Astrophysics Data System (ADS)

McCarthy, A.; Roques, C.; Selker, J. S.; Istok, J. D.; Pett-Ridge, J. C.

2015-12-01

Nitrate contamination in groundwater is a big challenge that will need to be addressed by hydrogeologists throughout the world. With a drinking water standard of 10mg/L of NO3-, innovative techniques will need to be pursued to ensure a decrease in drinking water nitrate concentration. At the pumping site scale, the influence and relationship between heterogeneous flow, mixing, and reactivity is not well understood. The purpose of this project is to incorporate both physical and chemical modeling techniques to better understand the effect of aquifer heterogeneities on autotrophic denitrification. We will investigate the link between heterogeneous hydraulic properties, transport, and the rate of autotrophic denitrification. Data collected in previous studies in laboratory experiments and pumping site scale experiments will be used to validate the models. The ultimate objective of this project is to develop a model in which such coupled processes are better understood resulting in best management practices of groundwater.

Effect of environmental conditions on the relationship between solar-induced fluorescence and gross primary productivity at an OzFlux grassland site

NASA Astrophysics Data System (ADS)

Verma, Manish; Schimel, David; Evans, Bradley; Frankenberg, Christian; Beringer, Jason; Drewry, Darren T.; Magney, Troy; Marang, Ian; Hutley, Lindsay; Moore, Caitlin; Eldering, Annmarie

2017-03-01

Recent studies have utilized coarse spatial and temporal resolution remotely sensed solar-induced fluorescence (SIF) for modeling terrestrial gross primary productivity (GPP) at regional scales. Although these studies have demonstrated the potential of SIF, there have been concerns about the ecophysiological basis of the relationship between SIF and GPP in different environmental conditions. Launched in 2014, the Orbiting Carbon Observatory-2 (OCO-2) has enabled fine-scale (1.3 by 2.5 km) retrievals of SIF that are comparable with measurements recorded at eddy covariance towers. In this study, we examine the effect of environmental conditions on the relationship of OCO-2 SIF with tower GPP over the course of a growing season at a well-characterized natural grassland site. Combining OCO-2 SIF and eddy covariance tower data with a canopy radiative transfer and an ecosystem model, we also assess the potential of OCO-2 SIF to constrain the estimates of Vcmax, one of the most important parameters in ecosystem models. Based on the results, we suggest that although environmental conditions play a role in determining the nature of relationship between SIF and GPP, overall, the linear relationship is more robust at ecosystem scale than the theory based on leaf-level processes might suggest. Our study also shows that the ability of SIF to constrain Vcmax is weak at the selected site.

Modeling opportunities and feasibility of siting wood-fired electrical generating facilities to facilitate landscape-scale fuel treatment with FIA BioSum.

Treesearch

Jeremy S. Fried; Glenn Christensen; Dale Weyermann; R. Jamie Barbour; Roger Fight; Bruce Hiserote; Guy Pinjuv

2005-01-01

Utilization of small diameter trees is viewed by many as the key to making landscape-scale fuel treatment financially feasible. But little capacity currently exists for utilizing such material and capacity of sufficient scale to have a significant impact on the economics of small diameter removals will only be added if predictable feedstocks can be assured. The FIA...

Next-Generation MDAC Discrimination Procedure Using Multi-Dimensional Spectral Analyses

DTIC Science & Technology

2007-09-01

explosions near the Lop Nor, Novaya Zemlya, Semipalatinsk , Nevada, and Indian test sites . We have computed regional phase spectra and are correcting... test sites as mainly due to differences in explosion P and S corner frequencies. Fisk (2007) used source model fits to estimate Pn, Pg, and Lg corner...frequencies for Nevada Test Site (NTS) explosions and found that Lg corner frequencies exhibit similar scaling with source size as for Pn and Pg

Commentary on: "Enzalutamide monotherapy in hormone-naive prostate cancer: primary analysis of an open-label, single-arm, phase 2 study." Tombal B, Borre M, Rathenborg P, Werbrouck P, Van Poppel H, Heidenreich A, Iversen P, Braeckman J, Heracek J, Baskin-Bey E, Ouatas T, Perabo F, Phung D, Hirmand M, Smith MR. Institut de Recherche Clinique, Université Catholique de Louvain, Brussels, Belgium. Electronic address: bertrand.tombal@uclouvain.be. Aarhus University Hospital, Aarhus, Denmark. Herlev Hospital, Herlev, Denmark. AZ Groeninge Kortrijk, Kortrijk, Belgium. UZ Leuven, Leuven, Belgium. Klinik und Poliklinik für Urologie, RWTH University Aachen, Aachen, Germany. Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. UZ Brussel, Brussels, Belgium. Univerzita Karlova v Praze, Prague, Czech Republic. Astellas Pharma Global Development, Leiden, Netherlands. Astellas Pharma Global Development, Northbrook, IL, USA. Medivation Inc, San Francisco, CA, USA. Massachusetts General Hospital Cancer Center, Boston, MA, USA: Lancet Oncol. 2014 May;15(6):592-600; doi: 10.1016/S1470-2045(14)70129-9. [Epub 2014 Apr 14].

PubMed

Trump, Donald

2016-05-01

The androgen receptor inhibitor enzalutamide is approved for the treatment of metastatic castration-resistant prostate cancer that has progressed on docetaxel. Our aim was to assess the activity and safety of enzalutamide monotherapy in men with hormone-naive prostate cancer. This trial is an ongoing open-label, single-arm, phase 2 study, done across 12 European sites. Men aged over 18 years with hormone-naive prostate cancer for whom hormone therapy was indicated, and who had noncastration levels of testosterone and prostate-specific antigen (PSA) of 2ng/mL or greater at screening, and an Eastern Cooperative Oncology Group score of 0, received oral enzalutamide 160mg/day. The primary outcome was the proportion of patients with an 80% or greater decline in PSA at week 25. All analyses included all patients who had received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT01302041. 67 men were enrolled into the study. 62 patients (92.5%, 95% CI: 86.2-98.8) had a decline in PSA of 80% or greater at week 25. The most commonly reported treatment-emergent adverse events up to week 25 were gynaecomastia (n = 24), fatigue (n = 23), nipple pain (n = 13), and hot flush (n = 12), all of which were of mild to moderate severity. Overall, 9 patients had a treatment-emergent adverse event of grade 3 or higher, most of which were reported in one patient each, except for pneumonia (grade 3, two patients) and hypertension (grade 3, four patients). Five patients reported serious adverse events, none of which were deemed to be treatment related. Our findings suggest that enzalutamide monotherapy in men with hormone-naive prostate cancer of varying severity provides a level of disease suppression and was generally well tolerated. These findings provide a rationale for further investigation of clinical response and outcomes with enzalutamide in noncastrated men with prostate cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

Modeling Groundwater Flow and Infiltration at Potential Low-Level Radioactive Waste Disposal Sites in Taiwan

NASA Astrophysics Data System (ADS)

Arnold, B. W.; Lee, C.; Ma, C.; Knowlton, R. G.

2006-12-01

Taiwan is evaluating representative sites for the potential disposal of low-level radioactive waste (LLW), including consideration of shallow land burial and cavern disposal concepts. A representative site for shallow land burial is on a small island in the Taiwan Strait with basalt bedrock. The shallow land burial concept includes an engineered cover to limit infiltration into the waste disposal cell. A representative site for cavern disposal is located on the southeast coast of Taiwan. The tunnel system for this disposal concept would be several hundred meters below the mountainous land surface in argillite bedrock. The LLW will consist of about 966,000 drums, primarily from the operation and decommissioning of four nuclear power plants. Sandia National Laboratories and the Institute of Nuclear Energy Research have collaborated to develop performance assessment models to evaluate the long-term safety of LLW disposal at these representative sites. Important components of the system models are sub-models of groundwater flow in the natural system and infiltration through the engineered cover for the shallow land burial concept. The FEHM software code was used to simulate groundwater flow in three-dimensional models at both sites. In addition, a higher-resolution two-dimensional model was developed to simulate flow through the engineered tunnel system at the cavern site. The HELP software was used to simulate infiltration through the cover at the island site. The primary objective of these preliminary models is to provide a modeling framework, given the lack of site-specific data and detailed engineering design specifications. The steady-state groundwater flow model at the island site uses a specified recharge boundary at the land surface and specified head at the island shoreline. Simulated groundwater flow vectors are extracted from the FEHM model along a cross section through one of the LLW disposal cells for utilization in radionuclide transport simulations in the performance assessment model with the BLT-MS software. Infiltration through the engineered cover is simulated to be about 3 mm/yr and 49 mm/yr, with and without a geomembrane layer, respectively. For the cavern LLW disposal site, the FEHM basin-scale flow model uses specified recharge flux, constant head at the ocean shoreline, and head-dependent flux boundaries along flowing streams. Groundwater flow vectors are extracted along a cross section for use in radionuclide transport simulations. Transport simulations indicate that a significant fraction of contaminants may ultimately discharge to nearby streams. FEHM flow simulations with the drift-scale model indicate that the flow rates within the backfilled tunnels may be more than two orders of magnitude lower than in the host rock. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

A process-based inventory model for landfill CH4 emissions inclusive of seasonal soil microclimate and CH4 oxidation

USDA-ARS?s Scientific Manuscript database

We have developed and field-validated an annual inventory model for California landfill CH4 emissions that incorporates both site-specific soil properties and soil microclimate modeling coupled to 0.5o scale global climatic models. Based on 1-D diffusion, CALMIM (California Landfill Methane Inventor...

Estimating occupancy in large landscapes: evaluation of amphibian monitoring in the greater Yellowstone ecosystem

USGS Publications Warehouse

Gould, William R.; Patla, Debra A.; Daley, Rob; Corn, Paul Stephen; Hossack, Blake R.; Bennetts, Robert E.; Peterson, Charles R.

2012-01-01

Monitoring of natural resources is crucial to ecosystem conservation, and yet it can pose many challenges. Annual surveys for amphibian breeding occupancy were conducted in Yellowstone and Grand Teton National Parks over a 4-year period (2006–2009) at two scales: catchments (portions of watersheds) and individual wetland sites. Catchments were selected in a stratified random sample with habitat quality and ease of access serving as strata. All known wetland sites with suitable habitat were surveyed within selected catchments. Changes in breeding occurrence of tiger salamanders, boreal chorus frogs, and Columbia-spotted frogs were assessed using multi-season occupancy estimation. Numerous a priori models were considered within an information theoretic framework including those with catchment and site-level covariates. Habitat quality was the most important predictor of occupancy. Boreal chorus frogs demonstrated the greatest increase in breeding occupancy at the catchment level. Larger changes for all 3 species were detected at the finer site-level scale. Connectivity of sites explained occupancy rates more than other covariates, and may improve understanding of the dynamic processes occurring among wetlands within this ecosystem. Our results suggest monitoring occupancy at two spatial scales within large study areas is feasible and informative.

A photosynthesis-based two-leaf canopy stomatal ...

EPA Pesticide Factsheets

A coupled photosynthesis-stomatal conductance model with single-layer sunlit and shaded leaf canopy scaling is implemented and evaluated in a diagnostic box model with the Pleim-Xiu land surface model (PX LSM) and ozone deposition model components taken directly from the meteorology and air quality modeling system—WRF/CMAQ (Weather Research and Forecast model and Community Multiscale Air Quality model). The photosynthesis-based model for PX LSM (PX PSN) is evaluated at a FLUXNET site for implementation against different parameterizations and the current PX LSM approach with a simple Jarvis function (PX Jarvis). Latent heat flux (LH) from PX PSN is further evaluated at five FLUXNET sites with different vegetation types and landscape characteristics. Simulated ozone deposition and flux from PX PSN are evaluated at one of the sites with ozone flux measurements. Overall, the PX PSN simulates LH as well as the PX Jarvis approach. The PX PSN, however, shows distinct advantages over the PX Jarvis approach for grassland that likely result from its treatment of C3 and C4 plants for CO2 assimilation. Simulations using Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) rather than LAI measured at each site assess how the model would perform with grid averaged data used in WRF/CMAQ. MODIS LAI estimates degrade model performance at all sites but one site having exceptionally old and tall trees. Ozone deposition velocity and ozone flux along with LH

Multiphase modeling of geologic carbon sequestration in saline aquifers.

PubMed

Bandilla, Karl W; Celia, Michael A; Birkholzer, Jens T; Cihan, Abdullah; Leister, Evan C

2015-01-01

Geologic carbon sequestration (GCS) is being considered as a climate change mitigation option in many future energy scenarios. Mathematical modeling is routinely used to predict subsurface CO2 and resident brine migration for the design of injection operations, to demonstrate the permanence of CO2 storage, and to show that other subsurface resources will not be degraded. Many processes impact the migration of CO2 and brine, including multiphase flow dynamics, geochemistry, and geomechanics, along with the spatial distribution of parameters such as porosity and permeability. In this article, we review a set of multiphase modeling approaches with different levels of conceptual complexity that have been used to model GCS. Model complexity ranges from coupled multiprocess models to simplified vertical equilibrium (VE) models and macroscopic invasion percolation models. The goal of this article is to give a framework of conceptual model complexity, and to show the types of modeling approaches that have been used to address specific GCS questions. Application of the modeling approaches is shown using five ongoing or proposed CO2 injection sites. For the selected sites, the majority of GCS models follow a simplified multiphase approach, especially for questions related to injection and local-scale heterogeneity. Coupled multiprocess models are only applied in one case where geomechanics have a strong impact on the flow. Owing to their computational efficiency, VE models tend to be applied at large scales. A macroscopic invasion percolation approach was used to predict the CO2 migration at one site to examine details of CO2 migration under the caprock. © 2015, National Ground Water Association.

Developing Conceptual Models of Biodegradation: Lessons Learned From a Long-Term Study of a Crude-Oil Contaminant Plume

NASA Astrophysics Data System (ADS)

Cozzarelli, I. M.; Esaid, H. I.; Bekins, B. A.; Eganhouse, R. P.; Baedecker, M.

2002-05-01

Assessment of natural attenuation as a remedial option requires understanding the long-term fate of contaminant compounds. The development of correct conceptual models of biodegradation requires observations at spatial and temporal scales appropriate for the reactions being measured. For example, the availability of electron acceptors such as solid-phase iron oxides may vary at the cm scale due to aquifer heterogeneities. Characterizing the distribution of these oxides may require small-scale measurements over time scales of tens of years in order to assess their impact on the fate of contaminants. The long-term study of natural attenuation of hydrocarbons in a contaminant plume near Bemidji, MN provides insight into how natural attenuation of hydrocarbons evolves over time. The sandy glacial-outwash aquifer at this USGS Toxic Substances Hydrology research site was contaminated by crude oil in 1979. During the 16 years that data have been collected the shape and extent of the contaminant plume changed as redox reactions, most notably iron reduction, progressed over time. Investigation of the controlling microbial reactions in this system required a systematic and multi-scaled approach. Early indications of plume shrinkage were observed over a time scale of a few years, based on observation well data. These changes were associated with iron reduction near the crude-oil source. The depletion of Fe (III) oxides near the contaminant source caused the dissolved iron concentrations to increase and spread downgradient at a rate of approximately 3 m/year. The zone of maximum benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations has also spread within the anoxic plume. Subsequent analyses of sediment and water, collected at small-scale cm intervals from cores in the contaminant plume, provided insight into the evolution of redox zones at smaller scales. Contaminants, such as ortho-xylene, that appeared to be contained near the oil source based on the larger-scale observation well data, were observed to be migrating in thin layers as the aquifer evolved to methanogenic conditions in narrow zones. The impact of adequately identifying the microbially mediated redox reactions was illustrated with a novel inverse modeling effort (using both the USGS solute transport and biodegradation code BIOMOC and the USGS universal inverse modeling code UCODE) to quantify field-scale hydrocarbon dissolution and biodegradation at the Bemidji site. Extensive historical data compiled at the Bemidji site were used, including 1352 concentration observations from 30 wells and 66 core sections. The simulations reproduced the general large-scale evolution of the plume, but the percent BTEX mass removed from the oil body after 18 years varied significantly, depending on which biodegradation conceptual model was used. The best fit was obtained for the iron-reduction conceptual model, which incorporated the finite availability of Fe (III) in the aquifer and reproduced the field observation that depletion of solid-phase iron resulted in increased downgradient transport of BTEX compounds. The predicted benzene plume 50 years after the spill showed significantly higher concentrations of benzene for the iron-reduction model compared to other conceptual models tested. This study demonstrates that the long-term sustainability of the electron acceptors is key to predicting the ultimate fate of the hydrocarbons. Assessing this evolution of redox processes and developing an adequate conceptual model required observations on multiple spatial scales over the course of many years.

Demonstrating the Uneven Importance of Fine-Scale Forest Structure on Snow Distributions using High Resolution Modeling

NASA Astrophysics Data System (ADS)

Broxton, P. D.; Harpold, A. A.; van Leeuwen, W.; Biederman, J. A.

2016-12-01

Quantifying the amount of snow in forested mountainous environments, as well as how it may change due to warming and forest disturbance, is critical given its importance for water supply and ecosystem health. Forest canopies affect snow accumulation and ablation in ways that are difficult to observe and model. Furthermore, fine-scale forest structure can accentuate or diminish the effects of forest-snow interactions. Despite decades of research demonstrating the importance of fine-scale forest structure (e.g. canopy edges and gaps) on snow, we still lack a comprehensive understanding of where and when forest structure has the largest impact on snowpack mass and energy budgets. Here, we use a hyper-resolution (1 meter spatial resolution) mass and energy balance snow model called the Snow Physics and Laser Mapping (SnowPALM) model along with LIDAR-derived forest structure to determine where spatial variability of fine-scale forest structure has the largest influence on large scale mass and energy budgets. SnowPALM was set up and calibrated at sites representing diverse climates in New Mexico, Arizona, and California. Then, we compared simulations at different model resolutions (i.e. 1, 10, and 100 m) to elucidate the effects of including versus not including information about fine scale canopy structure. These experiments were repeated for different prescribed topographies (i.e. flat, 30% slope north, and south-facing) at each site. Higher resolution simulations had more snow at lower canopy cover, with the opposite being true at high canopy cover. Furthermore, there is considerable scatter, indicating that different canopy arrangements can lead to different amounts of snow, even when the overall canopy coverage is the same. This modeling is contributing to the development of a high resolution machine learning algorithm called the Snow Water Artificial Network (SWANN) model to generate predictions of snow distributions over much larger domains, which has implications for improving land surface models that do not currently resolve or parameterize fine-scale canopy structure. In addition, these findings have implications for understanding the potential of different forest management strategies (i.e. thinning) based on local topography and climate to maximize the amount and retention of snow.

GPP/RE Partitioning of Long-term Network Flux Data as a Tool for Estimating Ecosystem-scale Ecophysiological Parameters of Grasslands and Croplands

NASA Astrophysics Data System (ADS)

Gilmanov, T. G.; Wylie, B. K.; Gu, Y.; Howard, D. M.; Zhang, L.

2013-12-01

The physiologically based model of canopy CO2 exchange by Thornly and Johnson (2000) modified to incorporate vapor pressure deficit (VPD) limitation of photosynthesis is a robust tool for partitioning tower network net CO2 exchange data into gross photosynthesis (GPP) and ecosystem respiration (RE) (Gilmanov et al. 2013a, b). In addition to 30-min and daily photosynthesis and respiration values, the procedure generates daily estimates and uncertainties of essential ecosystem-scale parameters such as apparent quantum yield ALPHA, photosynthetic capacity AMAX, convexity of light response THETA, gross ecological light-use efficiency LUE, daytime ecosystem respiration rate RDAY, and nighttime ecosystem respiration rate RNIGHT. These ecosystem-scale parameters are highly demanded by the modeling community and open opportunities for comparison with the rich data of leaf-level estimates of corresponding parameters available from physiological studies of previous decades. Based on the data for 70+ site-years of flux tower measurements at the non-forest sites of the Ameriflux network and the non-affiliated sites, we present results of the comparative analysis and multi-site synthesis of the magnitudes, uncertainties, patterns of seasonal and yearly dynamics, and spatiotemporal distribution of these parameters for grasslands and croplands of the conterminous United States (CONUS). Combining this site-level parameter data set with the rich spatiotemporal data sets of a remotely sensed vegetation index, weather and climate conditions, and site biophysical and geophysical features (phenology, photosynthetically active radiation, and soil water holding capacity) using methods of multivariate analysis (e.g., Cubist regression tree) offers new opportunities for predictive modeling and scaling-up of ecosystem-scale parameters of carbon cycling in grassland and agricultural ecosystems of CONUS (Zhang et al. 2011; Gu et al. 2012). REFERENCES Gilmanov TG, Baker JM, Bernacchi CJ, Billesbach DP, Burba GG, et al. (2013a). Productivity and CO2 exchange of the leguminous crops: Estimates from flux tower measurements. Agronomy J (submitted). Gilmanov TG, Wylie BK, Tieszen LL, Meyers TP, Baron VS, et al. (2013b). CO2 uptake and ecophysiological parameters of the grain crops of midcontinent North America: Estimates from flux tower measurements. Agric Ecosyst Environm 164: 162-175 Gu Y, Howard DM, Wylie BK, and Zhang L (2012). Mapping carbon flux uncertainty and selecting optimal locations for future flux towers in the Great Plains: Landscape Ecology, 27: 319-326. Thornley JHM., Johnson IR (2000). Plant and crop modelling. A mathematical approach to plant and crop physiology. The Blackburn Press, Caldwell, New Jersey. Zhang L, Wylie BK, Ji L, Gilmanov TG, Tieszen LL, Howard DM (2011). Upscaling carbon fluxes over the Great Plains grasslands: Sinks and sources. J Geophys Res G: Biogeosciences 116: G00J3

From Fractals to Fractional Vector Calculus: Measurement in the Correct Metric

NASA Astrophysics Data System (ADS)

Wheatcraft, S. W.; Meerschaert, M. M.; Mortensen, J.

2005-12-01

Traditional (stationary) stochastic theories have been fairly successful in reproducing transport behavior at relatively homogeneous field sites such as the Borden and Cape Code sites. However, the highly heterogeneous MADE site has produced tracer data that can not be adequately explained with traditional stochastic theories. In recent years, considerable attention has been focused on developing more sophisticated theories that can predict or reproduce the behavior of complex sites such as the MADE site. People began to realize that the model for geologic complexity may in many cases be very different than the model required for stochastic theory. Fractal approaches were useful in conceptualizing scale-invariant heterogeneity by demonstrating that scale dependant transport was just an artifact of our measurement system. Fractal media have dimensions larger than the dimension that measurement is taking place in, thus assuring the scale-dependence of parameters such as dispersivity. What was needed was a rigorous way to develop a theory that was consistent with the fractal dimension of the heterogeneity. The fractional advection-dispersion equation (FADE) was developed with this idea in mind. The second derivative in the dispersion term of the advection-dispersion equation is replaced with a fractional derivative. The order of differentiation, α, is fractional. Values of α in the range: 1 < α < 2 produce super-Fickian dispersion; in essence, the dispersion scaling is controlled by the value of α. When α = 2, the traditional advection-dispersion equation is recovered. The 1-D version of the FADE has been used successfully to back-predict tracer test behavior at several heterogeneous field sites, including the MADE site. It has been hypothesized that the order of differentiation in the FADE is equivalent to (or at least related to) the fractal dimension of the particle tracks (or geologic heterogeneity). With this way of thinking, one can think of the FADE as a governing equation written for the correct dimension, thus eliminating scale-dependent behavior. Before a generalized multi-dimensional form of the FADE can be developed, it has been necessary to develop a generalized fractional vector calculus. The authors have recently developed generalized canonical fractional forms of the gradient, divergence and curl. This fractional vector calculus will be useful in developing fractional forms of many governing equations in physics.

Comparative Modeling Studies of Boreal Water and Carbon Balance

NASA Technical Reports Server (NTRS)

Coughlan, J.; Peterson, David L. (Technical Monitor)

1997-01-01

The coordination of the modeling and field efforts for an Intensive Field Campaign (IFC) may resemble the chicken and egg dilemma. This session's theme advocates that early and proactive involvement by modeling teams can produce a scientific and operational benefit for the IFC and Experiment. This talk will provide some examples and suggestions originating from the NASA funded IFC's of the FIFE First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment, Oregon Transect Ecosystem Research (OTTER) and predominately Boreal Ecosystem-Atmosphere Study (BOREAS) Experiments. In February 1994 and prior to the final selection of the BOREAS study sites, a group of funded BOREAS investigators agreed to run their models with data for five community types representing the proposed tower flux sites. All participating models were given identical initial values and boundary conditions and driven with identical climate data. The objectives of the intercomparison exercise were: 1) compare simulation results of participating terrestrial, hydrological, and atmospheric models over selected time frames; 2) learn about model behavior and sensitivity to estimated boreal site and vegetation definitions; 3) prioritize BOREAS field data collection efforts supporting modeling studies; 4) identify individual model deficiencies as early as possible. Out of these objectives evolved some important coordination and science issues for the BOREAS Experiment that can be generalized to IFCs and long term archiving of the data. Some problems are acceptable because they are endemic to maintaining fair and open competition prior to the peer review process. Others are logistical and addressable through application of planning, management, and information sciences. This investigator has identified one source of measurement and model incompatibility that is manifest in the IFC scaling approach. Although intuitively obvious, scaling problems are already more formally defined in the Geography literature. An example of the scaling problem will be demonstrated with Vegetation/Ecosystem Mapping and Analysis Project (VEMAP) and OTTER data.

An integrated modeling approach for estimating the water quality benefits of conservation practices at the river basin scale.

PubMed

Santhi, C; Kannan, N; White, M; Di Luzio, M; Arnold, J G; Wang, X; Williams, J R

2014-01-01

The USDA initiated the Conservation Effects Assessment Project (CEAP) to quantify the environmental benefits of conservation practices at regional and national scales. For this assessment, a sampling and modeling approach is used. This paper provides a technical overview of the modeling approach used in CEAP cropland assessment to estimate the off-site water quality benefits of conservation practices using the Ohio River Basin (ORB) as an example. The modeling approach uses a farm-scale model, Agricultural Policy Environmental Extender (APEX), and a watershed scale model (the Soil and Water Assessment Tool [SWAT]) and databases in the Hydrologic Unit Modeling for the United States system. Databases of land use, soils, land use management, topography, weather, point sources, and atmospheric depositions were developed to derive model inputs. APEX simulates the cultivated cropland, Conserve Reserve Program land, and the practices implemented on them, whereas SWAT simulates the noncultivated land (e.g., pasture, range, urban, and forest) and point sources. Simulation results from APEX are input into SWAT. SWAT routes all sources, including APEX's, to the basin outlet through each eight-digit watershed. Each basin is calibrated for stream flow, sediment, and nutrient loads at multiple gaging sites and turned in for simulating the effects of conservation practice scenarios on water quality. Results indicate that sediment, nitrogen, and phosphorus loads delivered to the Mississippi River from ORB could be reduced by 16, 15, and 23%, respectively, due to current conservation practices. Modeling tools are useful to provide science-based information for assessing existing conservation programs, developing future programs, and developing insights on load reductions necessary for hypoxia in the Gulf of Mexico. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Associations of the Van Dyke's salamander (Plethodon vandykei) with geomorphic conditions in headwall seeps of the Cascade Range, Washington State.

Treesearch

A.P. McIntyre; R.A. Schmitz; C.M. Crisafulli

2006-01-01

We explored the association between Van Dyke's salamander (Plethodon vandykei) and hydrologic condition, geomorphology, and vegetation structure in headwall seeps in the Cascade Range of Washington State. We modeled occurrence of P. vandykei at three site scales: between seeps, within seeps, and between microhabitat sites...

Measured and modeled dry deposition velocities over the ESCOMPTE area

NASA Astrophysics Data System (ADS)

Michou, M.; Laville, P.; Serça, D.; Fotiadi, A.; Bouchou, P.; Peuch, V.-H.

2005-03-01

Measurements of the dry deposition velocity of ozone have been made by the eddy correlation method during ESCOMPTE (Etude sur Site pour COntraindre les Modèles de Pollution atmosphérique et de Transport d'Emissions). The strong local variability of natural ecosystems was sampled over several weeks in May, June and July 2001 for four sites with varying surface characteristics. The sites included a maize field, a Mediterranean forest, a Mediterranean shrub-land, and an almost bare soil. Measurements of nitrogen oxide deposition fluxes by the relaxed eddy correlation method have also been carried out at the same bare soil site. An evaluation of the deposition velocities computed by the surface module of the multi-scale Chemistry and Transport Model MOCAGE is presented. This module relies on a resistance approach, with a detailed treatment of the stomatal contribution to the surface resistance. Simulations at the finest model horizontal resolution (around 10 km) are compared to observations. If the seasonal variations are in agreement with the literature, comparisons between raw model outputs and observations, at the different measurement sites and for the specific observing periods, are contrasted. As the simulated meteorology at the scale of 10 km nicely captures the observed situations, the default set of surface characteristics (averaged at the resolution of a grid cell) appears to be one of the main reasons for the discrepancies found with observations. For each case, sensitivity studies have been performed in order to see the impact of adjusting the surface characteristics to the observed ones, when available. Generally, a correct agreement with the observations of deposition velocities is obtained. This advocates for a sub-grid scale representation of surface characteristics for the simulation of dry deposition velocities over such a complex area. Two other aspects appear in the discussion. Firstly, the strong influence of the soil water content to the plant response, specifically in conditions of stress, is confirmed. Second, we point out the difficulty in interpreting measurements of nitrogen oxide deposition velocities: a synergetic approach combining measurements and modeling is practical.

Scale-dependent factors affecting North American river otter distribution in the midwest

USGS Publications Warehouse

Jeffress, Mackenzie R.; Paukert, C.P.; Whittier, Joanna B.; Sandercock, B.K.; Gipson, P.S.

2011-01-01

The North American river otter (Lontra canadensis) is recovering from near extirpation throughout much of its range. Although reintroductions, trapping regulations and habitat improvements have led to the reestablishment of river otters in the Midwest, little is known about how their distribution is influenced by local- and landscape-scale habitat. We conducted river otter sign surveys from Jan. to Apr. in 2008 and 2009 in eastern Kansas to assess how local- and landscape-scale habitat factors affect river otter occupancy. We surveyed three to nine 400-m stretches of stream and reservoir shorelines for 110 sites and measured local-scale variables (e.g., stream order, land cover types) within a 100 m buffer of the survey site and landscape-scale variables (e.g., road density, land cover types) for Hydrological Unit Code 14 watersheds. We then used occupancy models that account for the probability of detection to estimate occupancy as a function of these covariates using Program PRESENCE. The best-fitting model indicated river otter occupancy increased with the proportion of woodland cover and decreased with the proportion of cropland and grassland cover at the local scale. Occupancy also increased with decreased shoreline diversity, waterbody density and stream density at the landscape scale. Occupancy was not affected by land cover or human disturbance at the landscape scale. Understanding the factors and scale important to river otter occurrence will be useful in identifying areas for management and continued restoration. ?? 2011, American Midland Naturalist.

Estimating the effects of land use at different scales on high ecological status in Irish rivers.

PubMed

Roberts, William M; Fealy, Reamonn M; Doody, Donnacha G; Jordan, Phil; Daly, Karen

2016-12-01

High ecological status at river sites is an indicator of minimal disturbance from anthropogenic activities and the presence of ecologically important species and communities. However, a lack of clarity on what factors cause sites to lose high ecological status is limiting the ability to maintain the quality of these sites. Examination of ecological status records at 508 high status river sites throughout the Republic of Ireland revealed that 337 had fallen below high status at some point between 2001 and 2012 due to changes in invertebrate communities. A geographical information system was used to characterise land use and environmental variables in the catchment, riparian and reach areas upstream of the sites. The relationships between these variables at the three spatial scales and whether or not river sites had maintained high ecological status were then estimated by multiple logistic regression and propensity modelling. The results indicated that grassland at either catchment or riparian scales had a greater negative impact on high ecological status than at the reach scale. This effect appeared to be strongest for upland, steeply sloping rivers that are subject to high rainfall, possibly due to the presence of sensitive biota and/or a greater potential for erosion. These results highlighted the need for better management of grassland upstream of the high status sites, with a focus on river alterations and critical source areas of nutrients, sediments and pesticides that are hydrologically connected to the river. Sustainable management practices and land use planning in those areas will need to be considered carefully if the aim of maintaining high ecological status at river sites is to be achieved. Copyright © 2016 Elsevier B.V. All rights reserved.

Improved simulation of group averaged CO2 surface concentrations using GEOS-Chem and fluxes from VEGAS

NASA Astrophysics Data System (ADS)

Chen, Z. H.; Zhu, J.; Zeng, N.

2013-01-01

CO2 measurements have been combined with simulated CO2 distributions from a transport model in order to produce the optimal estimates of CO2 surface fluxes in inverse modeling. However one persistent problem in using model-observation comparisons for this goal relates to the issue of compatibility. Observations at a single site reflect all underlying processes of various scales that usually cannot be fully resolved by model simulations at the grid points nearest the site due to lack of spatial or temporal resolution or missing processes in models. In this article we group site observations of multiple stations according to atmospheric mixing regimes and surface characteristics. The group averaged values of CO2 concentration from model simulations and observations are used to evaluate the regional model results. Using the group averaged measurements of CO2 reduces the noise of individual stations. The difference of group averaged values between observation and modeled results reflects the uncertainties of the large scale flux in the region where the grouped stations are. We compared the group averaged values between model results with two biospheric fluxes from the model Carnegie-Ames-Stanford-Approach (CASA) and VEgetation-Global-Atmosphere-Soil (VEGAS) and observations to evaluate the regional model results. Results show that the modeling group averaged values of CO2 concentrations in all regions with fluxes from VEGAS have significant improvements for most regions. There is still large difference between two model results and observations for grouped average values in North Atlantic, Indian Ocean, and South Pacific Tropics. This implies possible large uncertainties in the fluxes there.

Meteorological Predictions in Support of the Mars Science Laboratory Entry, Descent and Landing

NASA Astrophysics Data System (ADS)

Rothchild, A.; Rafkin, S. C.; Pielke, R. A., Sr.

2010-12-01

The Mars Science Laboratory (MSL) entry, descent, and landing (EDL) system employs a standard parachute strategy followed by a new sky crane concept where the rover is lowered to the ground via a tether from a hovering entry vehicle. As with previous missions, EDL system performance is sensitive to atmospheric conditions. While some observations characterizing the mean, large-scale atmospheric temperature and density data are available, there is effectively no information on the atmospheric conditions and variability at the scale that directly affects the spacecraft. In order to evaluate EDL system performance and to assess landing hazards and risk, it is necessary to simulate the atmosphere with a model that provides data at the appropriate spatial and temporal scales. Models also permit the study of the impact of the highly variable atmospheric dust loading on temperature, density and winds. There are four potential MSL landing sites: Mawrth Valle (22.3 N, 16.5W) , Gale Crater (5.4S, 137.7E), Holden Crater (26.1S, 34W), and Eberswalde Crater (24S, 33W). The final selection of the landing site will balance potential science return against landing and operational risk. Atmospheric modeling studies conducted with the Mars Regional Atmospheric Modeling System (MRAMS) is an integral part of the selection process. At each of the landing sites, a variety of simulations are conducted. The first type of simulations provide baseline predictions under nominal atmospheric dust loading conditions within the landing site window of ~Ls 150-170. The second type of simulation explores situations with moderate and high global atmospheric dust loading. The final type of simulation investigates the impact of local dust disturbances at the landing site. Mean and perturbation fields from each type of simulation at each of the potential landing sites are presented in comparison with the engineering performance limitations for the MSL EDL system. Within the lowest scale height, winds are strongly influenced by the local and regional topography and are highly variable in both space and time. Convective activity in the afternoon produces deep vertical circulations anchored primarily to topography. Aloft, winds become increasingly dominated by the large-scale circulation, but with gravity wave perturbations forced by both topography and boundary layer convective activity. The mean density field is tied directly to the level of dust loading; higher dust results in decreased densities and overall warming of the atmospheric column. In local and regional dust storm scenarios, winds are found to be enhanced, particularly in regions of active dust lifting. Local reductions in density are also pronounced. At present, the predicted mean and perturbation fields from all the simulations appear to fall within the engineering requirements, but not always comfortably so. This is in contrast to proposed landing sites for the Mars Exploration Rover mission, where the atmospheric environment presented unacceptable risk. Ongoing work is underway to confirm that atmospheric conditions will permit safe EDL operations with a tolerable level of risk.

A nested observation and model approach to non linear groundwater surface water interactions.

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.

2009-04-01

Surface water quality measurements in The Netherlands are scattered in time and space. Therefore, water quality status and its variations and trends are difficult to determine. In order to reach the water quality goals according to the European Water Framework Directive, we need to improve our understanding of the dynamics of surface water quality and the processes that affect it. In heavily drained lowland catchment groundwater influences the discharge towards the surface water network in many complex ways. Especially a strong seasonal contracting and expanding system of discharging ditches and streams affects discharge and solute transport. At a tube drained field site the tube drain flux and the combined flux of all other flow routes toward a stretch of 45 m of surface water have been measured for a year. Also the groundwater levels at various locations in the field and the discharge at two nested catchment scales have been monitored. The unique reaction of individual flow routes on rainfall events at the field site allowed us to separate the discharge at a 4 ha catchment and at a 6 km2 into flow route contributions. The results of this nested experimental setup combined with the results of a distributed hydrological model has lead to the formulation of a process model approach that focuses on the spatial variability of discharge generation driven by temporal and spatial variations in groundwater levels. The main idea of this approach is that discharge is not generated by catchment average storages or groundwater heads, but is mainly generated by points scale extremes i.e. extreme low permeability, extreme high groundwater heads or extreme low surface elevations, all leading to catchment discharge. We focused on describing the spatial extremes in point scale storages and this led to a simple and measurable expression that governs the non-linear groundwater surface water interaction. We will present the analysis of the field site data to demonstrate the potential of nested-scale, high frequency observations. The distributed hydrological model results will be used to show transient catchment scale relations between groundwater levels and discharges. These analyses lead to a simple expression that can describe catchment scale groundwater surface water interactions.

Temporal scaling of groundwater level fluctuations near a stream

USGS Publications Warehouse

Schilling, K.E.; Zhang, Y.-K.

2012-01-01

Temporal scaling in stream discharge and hydraulic heads in riparian wells was evaluated to determine the feasibility of using spectral analysis to identify potential surface and groundwater interaction. In floodplains where groundwater levels respond rapidly to precipitation recharge, potential interaction is established if the hydraulic head (h) spectrum of riparian groundwater has a power spectral density similar to stream discharge (Q), exhibiting a characteristic breakpoint between high and low frequencies. At a field site in Walnut Creek watershed in central Iowa, spectral analysis of h in wells located 1 m from the channel edge showed a breakpoint in scaling very similar to the spectrum of Q (~20 h), whereas h in wells located 20 and 40 m from the channel showed temporal scaling from 1 to 10,000 h without a well-defined breakpoint. The spectral exponent (??) in the riparian zone decreased systematically from the channel into the floodplain as groundwater levels were increasingly dominated by white noise groundwater recharge. The scaling pattern of hydraulic head was not affected by land cover type, although the number of analyses was limited and site conditions were variable among sites. Spectral analysis would not replace quantitative tracer or modeling studies, but the method may provide a simple means of confirming potential interaction at some sites. ?? 2011, The Author(s). Ground Water ?? 2011, National Ground Water Association.

Temporal scaling of groundwater level fluctuations near a stream.

PubMed

Schilling, Keith E; Zhang, You-Kuan

2012-01-01

Temporal scaling in stream discharge and hydraulic heads in riparian wells was evaluated to determine the feasibility of using spectral analysis to identify potential surface and groundwater interaction. In floodplains where groundwater levels respond rapidly to precipitation recharge, potential interaction is established if the hydraulic head (h) spectrum of riparian groundwater has a power spectral density similar to stream discharge (Q), exhibiting a characteristic breakpoint between high and low frequencies. At a field site in Walnut Creek watershed in central Iowa, spectral analysis of h in wells located 1 m from the channel edge showed a breakpoint in scaling very similar to the spectrum of Q (∼20 h), whereas h in wells located 20 and 40 m from the channel showed temporal scaling from 1 to 10,000 h without a well-defined breakpoint. The spectral exponent (β) in the riparian zone decreased systematically from the channel into the floodplain as groundwater levels were increasingly dominated by white noise groundwater recharge. The scaling pattern of hydraulic head was not affected by land cover type, although the number of analyses was limited and site conditions were variable among sites. Spectral analysis would not replace quantitative tracer or modeling studies, but the method may provide a simple means of confirming potential interaction at some sites. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

Model-based performance and energy analyses of reverse osmosis to reuse wastewater in a PVC production site.

PubMed

Hu, Kang; Fiedler, Thorsten; Blanco, Laura; Geissen, Sven-Uwe; Zander, Simon; Prieto, David; Blanco, Angeles; Negro, Carlos; Swinnen, Nathalie

2017-11-10

A pilot-scale reverse osmosis (RO) followed behind a membrane bioreactor (MBR) was developed for the desalination to reuse wastewater in a PVC production site. The solution-diffusion-film model (SDFM) based on the solution-diffusion model (SDM) and the film theory was proposed to describe rejections of electrolyte mixtures in the MBR effluent which consists of dominant ions (Na + and Cl - ) and several trace ions (Ca 2+ , Mg 2+ , K + and SO 4 2- ). The universal global optimisation method was used to estimate the ion permeability coefficients (B) and mass transfer coefficients (K) in SDFM. Then, the membrane performance was evaluated based on the estimated parameters which demonstrated that the theoretical simulations were in line with the experimental results for the dominant ions. Moreover, an energy analysis model with the consideration of limitation imposed by the thermodynamic restriction was proposed to analyse the specific energy consumption of the pilot-scale RO system in various scenarios.

Between-Site Differences in the Scale of Dispersal and Gene Flow in Red Oak

PubMed Central

Moran, Emily V.; Clark, James S.

2012-01-01

Background Nut-bearing trees, including oaks (Quercus spp.), are considered to be highly dispersal limited, leading to concerns about their ability to colonize new sites or migrate in response to climate change. However, estimating seed dispersal is challenging in species that are secondarily dispersed by animals, and differences in disperser abundance or behavior could lead to large spatio-temporal variation in dispersal ability. Parentage and dispersal analyses combining genetic and ecological data provide accurate estimates of current dispersal, while spatial genetic structure (SGS) can shed light on past patterns of dispersal and establishment. Methodology and Principal Findings In this study, we estimate seed and pollen dispersal and parentage for two mixed-species red oak populations using a hierarchical Bayesian approach. We compare these results to those of a genetic ML parentage model. We also test whether observed patterns of SGS in three size cohorts are consistent with known site history and current dispersal patterns. We find that, while pollen dispersal is extensive at both sites, the scale of seed dispersal differs substantially. Parentage results differ between models due to additional data included in Bayesian model and differing genotyping error assumptions, but both indicate between-site dispersal differences. Patterns of SGS in large adults, small adults, and seedlings are consistent with known site history (farmed vs. selectively harvested), and with long-term differences in seed dispersal. This difference is consistent with predator/disperser satiation due to higher acorn production at the low-dispersal site. While this site-to-site variation results in substantial differences in asymptotic spread rates, dispersal for both sites is substantially lower than required to track latitudinal temperature shifts. Conclusions Animal-dispersed trees can exhibit considerable spatial variation in seed dispersal, although patterns may be surprisingly constant over time. However, even under favorable conditions, migration in heavy-seeded species is likely to lag contemporary climate change. PMID:22563504

Methane emissions from floodplains in the Amazon Basin: towards a process-based model for global applications

NASA Astrophysics Data System (ADS)

Ringeval, B.; Houweling, S.; van Bodegom, P. M.; Spahni, R.; van Beek, R.; Joos, F.; Röckmann, T.

2013-10-01

Tropical wetlands are estimated to represent about 50% of the natural wetland emissions and explain a large fraction of the observed CH4 variability on time scales ranging from glacial-interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH4 emissions. This study documents the first regional-scale, process-based model of CH4 emissions from tropical floodplains. The LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was modified to represent floodplain hydrology, vegetation and associated CH4 emissions. The extent of tropical floodplains was prescribed using output from the spatially-explicit hydrology model PCR-GLOBWB. We introduced new Plant Functional Types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote sensing datasets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX simulated CH4 flux densities are in reasonable agreement with observations at the field scale but with a~tendency to overestimate the flux observed at specific sites. In addition, the model did not reproduce between-site variations or between-year variations within a site. Unfortunately, site informations are too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH4 emissions. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr-1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin modulated emissions by about 20%. Correcting the LPX simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the seasonality in CH4 emissions. The Inter Annual Variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is account for, but still remains lower than in most of WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH4 emissions of the Amazon Basin. Our results stress the need for more research to constrain floodplain CH4 emissions and their temporal variability.

Upscaling of nanoparticle transport in porous media under unfavorable conditions: Pore scale to Darcy scale

NASA Astrophysics Data System (ADS)

Seetha, N.; Raoof, Amir; Mohan Kumar, M. S.; Majid Hassanizadeh, S.

2017-05-01

Transport and deposition of nanoparticles in porous media is a multi-scale problem governed by several pore-scale processes, and hence, it is critical to link the processes at pore scale to the Darcy-scale behavior. In this study, using pore network modeling, we develop correlation equations for deposition rate coefficients for nanoparticle transport under unfavorable conditions at the Darcy scale based on pore-scale mechanisms. The upscaling tool is a multi-directional pore-network model consisting of an interconnected network of pores with variable connectivities. Correlation equations describing the pore-averaged deposition rate coefficients under unfavorable conditions in a cylindrical pore, developed in our earlier studies, are employed for each pore element. Pore-network simulations are performed for a wide range of parameter values to obtain the breakthrough curves of nanoparticle concentration. The latter is fitted with macroscopic 1-D advection-dispersion equation with a two-site linear reversible deposition accounting for both equilibrium and kinetic sorption. This leads to the estimation of three Darcy-scale deposition coefficients: distribution coefficient, kinetic rate constant, and the fraction of equilibrium sites. The correlation equations for the Darcy-scale deposition coefficients, under unfavorable conditions, are provided as a function of measurable Darcy-scale parameters, including: porosity, mean pore throat radius, mean pore water velocity, nanoparticle radius, ionic strength, dielectric constant, viscosity, temperature, and surface potentials of the particle and grain surfaces. The correlation equations are found to be consistent with the available experimental results, and in qualitative agreement with Colloid Filtration Theory for all parameters, except for the mean pore water velocity and nanoparticle radius.

Numerical Modeling of Artificial Recharge: Determining Spatial/Temporal Sampling Resolution to Quantify Infiltration Rates and Effective Hydraulic Conductivity

NASA Astrophysics Data System (ADS)

Glose, T. J.; Hausner, M. B.; Lowry, C.

2016-12-01

The accurate, fine scale quantification of groundwater-surface water (GW-SW) interactions over large expanses in hydrologic systems is a fundamental need in order to accurately characterize critical zones of biogeochemical transformation and fluxes, as well as to provide insight into near-surface geologic heterogeneity. Paired fiber-optic distributed temperature sensing (FO-DTS) is a tool that is capable of synoptically sampling hydrologic systems, allowing GW-SW interactions to be examined at a fine scale over large distances. Within managed aquifer recharge (MAR) sites, differential recharge dynamics controlled by bed clogging and subsurface heterogeneity dictate the effectiveness of these sites at infiltrating water. Numerical modeling indicates that the use of paired FO-DTS in an MAR site can provide accurate quantification of flux at the GW-SW interface, as well as provide insight to the areal extent of geologic heterogeneity in the subsurface. However, the lateral and vertical separation of the fiber-optic cables is of vital importance. Here we present a 2-D, fully coupled groundwater flow and heat transport model with prescribed heterogeneity. Following a forward modeling approach, realizations simulating varying fiber-optic cable positioning, differential bed clogging, and hydraulic conductivity variability were analyzed over a suite of scenarios. The results from the model were then used as observations to calculate groundwater recharge rates and calibration targets for an inverse model to estimate subsurface heterogeneity.

Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

NASA Astrophysics Data System (ADS)

Kathrin Hassler, Sibylle; Weiler, Markus; Blume, Theresa

2018-01-01

Transpiration is a key process in the hydrological cycle, and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation and evaluation of hydrological and soil-vegetation-atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology and soils, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls.We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites across a 290 km2 catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocity and derived sap flow patterns of these 61 trees, and we determined the importance of the different controls.Results indicate that a combination of mainly tree- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, geology and aspect. For sap flow we included only the stand- and site-specific predictors in the models to ensure variable independence. Of those, geology and aspect were most important. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, are correlated to the temporal dynamics of potential evaporation. We conclude that transpiration estimates on the landscape scale would benefit from not only consideration of hydro-meteorological drivers, but also tree, stand and site characteristics in order to improve the spatial and temporal representation of transpiration for hydrological and soil-vegetation-atmosphere transfer models.

Automating an integrated spatial data-mining model for landfill site selection

NASA Astrophysics Data System (ADS)

Abujayyab, Sohaib K. M.; Ahamad, Mohd Sanusi S.; Yahya, Ahmad Shukri; Ahmad, Siti Zubaidah; Aziz, Hamidi Abdul

2017-10-01

An integrated programming environment represents a robust approach to building a valid model for landfill site selection. One of the main challenges in the integrated model is the complicated processing and modelling due to the programming stages and several limitations. An automation process helps avoid the limitations and improve the interoperability between integrated programming environments. This work targets the automation of a spatial data-mining model for landfill site selection by integrating between spatial programming environment (Python-ArcGIS) and non-spatial environment (MATLAB). The model was constructed using neural networks and is divided into nine stages distributed between Matlab and Python-ArcGIS. A case study was taken from the north part of Peninsular Malaysia. 22 criteria were selected to utilise as input data and to build the training and testing datasets. The outcomes show a high-performance accuracy percentage of 98.2% in the testing dataset using 10-fold cross validation. The automated spatial data mining model provides a solid platform for decision makers to performing landfill site selection and planning operations on a regional scale.

CO 2 leakage impacts on shallow groundwater. Field-scale reactive-transport simulations informed by observations at a natural analog site

DOE PAGES

Keating, Elizabeth H.; Hakala, J. Alexandra; Viswanathan, Hari; ...

2013-03-01

It is challenging to predict the degree to which shallow groundwater might be affected by leaks from a CO 2 sequestration reservoir, particularly over long time scales and large spatial scales. In this study observations at a CO 2 enriched shallow aquifer natural analog were used to develop a predictive model which is then used to simulate leakage scenarios. This natural analog provides the opportunity to make direct field observations of groundwater chemistry in the presence of elevated CO 2, to collect aquifer samples and expose them to CO 2 under controlled conditions in the laboratory, and to test themore » ability of multiphase reactive transport models to reproduce measured geochemical trends at the field-scale. The field observations suggest that brackish water entrained with the upwelling CO 2 are a more significant source of trace metals than in situ mobilization of metals due to exposure to CO 2. The study focuses on a single trace metal of concern at this site: U. Experimental results indicate that cation exchange/adsorption and dissolution/precipitation of calcite containing trace amounts of U are important reactions controlling U in groundwater at this site, and that the amount of U associated with calcite is fairly well constrained. Simulations incorporating these results into a 3-D multi-phase reactive transport model are able to reproduce the measured ranges and trends between pH, pCO 2, Ca, total C, U and Cl -at the field site. Although the true fluxes at the natural analog site are unknown, the cumulative CO 2 flux inferred from these simulations are approximately equivalent to 37.8E-3 MT, approximately corresponding to a .001% leak rate for injection at a large (750 MW) power plant. The leakage scenario simulations suggest that if the leak only persists for a short time the volume of aquifer contaminated by CO 2-induced mobilization of U will be relatively small, yet persistent over 100 a.« less

Scaling Laws of Discrete-Fracture-Network Models

NASA Astrophysics Data System (ADS)

Philippe, D.; Olivier, B.; Caroline, D.; Jean-Raynald, D.

2006-12-01

The statistical description of fracture networks through scale still remains a concern for geologists, considering the complexity of fracture networks. A challenging task of the last 20-years studies has been to find a solid and rectifiable rationale to the trivial observation that fractures exist everywhere and at all sizes. The emergence of fractal models and power-law distributions quantifies this fact, and postulates in some ways that small-scale fractures are genetically linked to their larger-scale relatives. But the validation of these scaling concepts still remains an issue considering the unreachable amount of information that would be necessary with regards to the complexity of natural fracture networks. Beyond the theoretical interest, a scaling law is a basic and necessary ingredient of Discrete-Fracture-Network models (DFN) that are used for many environmental and industrial applications (groundwater resources, mining industry, assessment of the safety of deep waste disposal sites, ..). Indeed, such a function is necessary to assemble scattered data, taken at different scales, into a unified scaling model, and to interpolate fracture densities between observations. In this study, we discuss some important issues related to scaling laws of DFN: - We first describe a complete theoretical and mathematical framework that takes account of both the fracture- size distribution and the fracture clustering through scales (fractal dimension). - We review the scaling laws that have been obtained, and we discuss the ability of fracture datasets to really constrain the parameters of the DFN model. - And finally we discuss the limits of scaling models.

Determination of antennae patterns and radar reflection characteristics of aircraft

NASA Astrophysics Data System (ADS)

Bothe, H.; MacDonald, D.; Pool, A.

1986-05-01

The different types of aircraft antennas, their radiation characteristics and their preferred siting on the airframe are described. Emphasis is placed on the various methods for determining aircraft antenna radiation patterns (ARP) and advantages, disadvantages and limitations of each method are indicated. Mathematical modelling, model measurements and in-flight measurements in conjunction with the applied flight test techniques are included. Examples of practical results are given. Methods of determining aircraft radar characteristics are also described, indicating advantages, disadvantages and limitations of each method. Relevant fundamentals of radar theory are included only as necessary to appreciation of the real meaning of radar cross section (RCS) and angular glint. The measuring methods included are dynamic full-scale, static full-scale, sub-scale optical, ultrasonic and radio modelling. References are made to RCS measuring facilities in the USA and Europe and the UK Radio Modelling Facility is used extensively to exemplify the sub scale technique.

Advanced Atmospheric Modeling for Emergency Response.

NASA Astrophysics Data System (ADS)

Fast, Jerome D.; O'Steen, B. Lance; Addis, Robert P.

1995-03-01

Atmospheric transport and diffusion models are an important part of emergency response systems for industrial facilities that have the potential to release significant quantities of toxic or radioactive material into the atmosphere. An advanced atmospheric transport and diffusion modeling system for emergency response and environmental applications, based upon a three-dimensional mesoscale model, has been developed for the U.S. Department of Energy's Savannah River Site so that complex, time-dependent flow fields not explicitly measured can be routinely simulated. To overcome some of the current computational demands of mesoscale models, two operational procedures for the advanced atmospheric transport and diffusion modeling system are described including 1) a semiprognostic calculation to produce high-resolution wind fields for local pollutant transport in the vicinity of the Savannah River Site and 2) a fully prognostic calculation to produce a regional wind field encompassing the southeastern United States for larger-scale pollutant problems. Local and regional observations and large-scale model output are used by the mesoscale model for the initial conditions, lateral boundary conditions, and four-dimensional data assimilation procedure. This paper describes the current status of the modeling system and presents two case studies demonstrating the capabilities of both modes of operation. While the results from the case studies shown in this paper are preliminary and certainly not definitive, they do suggest that the mesoscale model has the potential for improving the prognostic capabilities of atmospheric modeling for emergency response at the Savannah River Site. Long-term model evaluation will be required to determine under what conditions significant forecast errors exist.

A photosynthesis-based two-leaf canopy stomatal conductance model for meteorology and air quality modeling with WRF/CMAQ PX LSM

NASA Astrophysics Data System (ADS)

Ran, Limei; Pleim, Jonathan; Song, Conghe; Band, Larry; Walker, John T.; Binkowski, Francis S.

2017-02-01

A coupled photosynthesis-stomatal conductance model with single-layer sunlit and shaded leaf canopy scaling is implemented and evaluated in a diagnostic box model with the Pleim-Xiu land surface model (PX LSM) and ozone deposition model components taken directly from the meteorology and air quality modeling system - WRF/CMAQ (Weather Research and Forecast model and Community Multiscale Air Quality model). The photosynthesis-based model for PX LSM (PX PSN) is evaluated at a FLUXNET site for implementation against different parameterizations and the current PX LSM approach with a simple Jarvis function (PX Jarvis). Latent heat flux (LH) from PX PSN is further evaluated at five FLUXNET sites with different vegetation types and landscape characteristics. Simulated ozone deposition and flux from PX PSN are evaluated at one of the sites with ozone flux measurements. Overall, the PX PSN simulates LH as well as the PX Jarvis approach. The PX PSN, however, shows distinct advantages over the PX Jarvis approach for grassland that likely result from its treatment of C3 and C4 plants for CO2 assimilation. Simulations using Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) rather than LAI measured at each site assess how the model would perform with grid averaged data used in WRF/CMAQ. MODIS LAI estimates degrade model performance at all sites but one site having exceptionally old and tall trees. Ozone deposition velocity and ozone flux along with LH are simulated especially well by the PX PSN compared to significant overestimation by the PX Jarvis for a grassland site.

Multi-scale occupancy estimation and modelling using multiple detection methods

USGS Publications Warehouse

Nichols, James D.; Bailey, Larissa L.; O'Connell, Allan F.; Talancy, Neil W.; Grant, Evan H. Campbell; Gilbert, Andrew T.; Annand, Elizabeth M.; Husband, Thomas P.; Hines, James E.

2008-01-01

Occupancy estimation and modelling based on detection–nondetection data provide an effective way of exploring change in a species’ distribution across time and space in cases where the species is not always detected with certainty. Today, many monitoring programmes target multiple species, or life stages within a species, requiring the use of multiple detection methods. When multiple methods or devices are used at the same sample sites, animals can be detected by more than one method.We develop occupancy models for multiple detection methods that permit simultaneous use of data from all methods for inference about method-specific detection probabilities. Moreover, the approach permits estimation of occupancy at two spatial scales: the larger scale corresponds to species’ use of a sample unit, whereas the smaller scale corresponds to presence of the species at the local sample station or site.We apply the models to data collected on two different vertebrate species: striped skunks Mephitis mephitis and red salamanders Pseudotriton ruber. For striped skunks, large-scale occupancy estimates were consistent between two sampling seasons. Small-scale occupancy probabilities were slightly lower in the late winter/spring when skunks tend to conserve energy, and movements are limited to males in search of females for breeding. There was strong evidence of method-specific detection probabilities for skunks. As anticipated, large- and small-scale occupancy areas completely overlapped for red salamanders. The analyses provided weak evidence of method-specific detection probabilities for this species.Synthesis and applications. Increasingly, many studies are utilizing multiple detection methods at sampling locations. The modelling approach presented here makes efficient use of detections from multiple methods to estimate occupancy probabilities at two spatial scales and to compare detection probabilities associated with different detection methods. The models can be viewed as another variation of Pollock's robust design and may be applicable to a wide variety of scenarios where species occur in an area but are not always near the sampled locations. The estimation approach is likely to be especially useful in multispecies conservation programmes by providing efficient estimates using multiple detection devices and by providing device-specific detection probability estimates for use in survey design.

Geologic uncertainty in a regulatory environment: An example from the potential Yucca Mountain nuclear waste repository site

NASA Astrophysics Data System (ADS)

Rautman, C. A.; Treadway, A. H.

1991-11-01

Regulatory geologists are concerned with predicting the performance of sites proposed for waste disposal or for remediation of existing pollution problems. Geologic modeling of these sites requires large-scale expansion of knowledge obtained from very limited sampling. This expansion induces considerable uncertainty into the geologic models of rock properties that are required for modeling the predicted performance of the site. One method for assessing this uncertainty is through nonparametric geostatistical simulation. Simulation can produce a series of equiprobable models of a rock property of interest. Each model honors measured values at sampled locations, and each can be constructed to emulate both the univariate histogram and the spatial covariance structure of the measured data. Computing a performance model for a number of geologic simulations allows evaluation of the effects of geologic uncertainty. A site may be judged acceptable if the number of failures to meet a particular performance criterion produced by these computations is sufficiently low. A site that produces too many failures may be either unacceptable or simply inadequately described. The simulation approach to addressing geologic uncertainty is being applied to the potential high-level nuclear waste repository site at Yucca Mountain, Nevada, U.S.A. Preliminary geologic models of unsaturated permeability have been created that reproduce observed statistical properties reasonably well. A spread of unsaturated groundwater travel times has been computed that reflects the variability of those geologic models. Regions within the simulated models exhibiting the greatest variability among multiple runs are candidates for obtaining the greatest reduction in uncertainty through additional site characterization.

Counting on β-Diversity to Safeguard the Resilience of Estuaries

PubMed Central

de Juan, Silvia; Thrush, Simon F.; Hewitt, Judi E.

2013-01-01

Coastal ecosystems are often stressed by non-point source and cumulative effects that can lead to local-scale community homogenisation and a concomitant loss of large-scale ecological connectivity. Here we investigate the use of β-diversity as a measure of both community heterogeneity and ecological connectivity. To understand the consequences of different environmental scenarios on heterogeneity and connectivity, it is necessary to understand the scale at which different environmental factors affect β-diversity. We sampled macrofauna from intertidal sites in nine estuaries from New Zealand’s North Island that represented different degrees of stress derived from land-use. We used multiple regression models to identify relationships between β-diversity and local sediment variables, factors related to the estuarine and catchment hydrodynamics and morphology and land-based stressors. At local scales, we found higher β-diversity at sites with a relatively high total richness. At larger scales, β-diversity was positively related to γ-diversity, suggesting that a large regional species pool was linked with large-scale heterogeneity in these systems. Local environmental heterogeneity influenced β-diversity at both local and regional scales, although variables at the estuarine and catchment scales were both needed to explain large scale connectivity. The estuaries expected a priori to be the most stressed exhibited higher variance in community dissimilarity between sites and connectivity to the estuary species pool. This suggests that connectivity and heterogeneity metrics could be used to generate early warning signals of cumulative stress. PMID:23755252

An objective and reproducible landform and topography description approach based on digital terrain analysis used for soil profile site characteristics

NASA Astrophysics Data System (ADS)

Gruber, Fabian E.; Baruck, Jasmin; Hastik, Richard; Geitner, Clemens

2015-04-01

All major soil description and classification systems, including the World Reference Base (WRB) and the German Soil description guidelines (KA5), require the characterization of landform and topography for soil profile sites. This is commonly done at more than one scale, for instance at macro-, meso- and micro scale. However, inherent when humans perform such a task, different surveyors will reach different conclusions due to their subjective perception of landscape structure, based on their individual mind-model of soil-landscape structure, emphasizing different aspects and scales of the landscape. In this study we apply a work-flow using the GRASS GIS extension module r.geomorphon to make use of high resolution digital elevation models (DEMs) to characterize the landform elements and topography of soil profile sites at different scales, and compare the results with a large number of soil profile site descriptions performed during the course of forestry surveys in South and North Tyrol (Italy and Austria, respectively). The r.geomorphon extension module for the open source geographic information system GRASS GIS applies a pattern recognition algorithm to delineate landform elements based on an input DEM. For each raster cell it computes and characterizes the visible neighborhood using line-of-sight calculations and then applies a lookup-table to classify the raster cell into one of ten landform elements (flat, peak, ridge, shoulder, slope, spur, hollow, footslope, valley and pit). The input parameter search radius (L) represents the maximum number of pixels for line-of-sight calculation, resulting in landforms larger than L to be split into landform components. The use of these visibility calculations makes this landform delineation approach suitable for comparison with the landform descriptions of soil surveyors, as their spatial perception of the landscape surrounding a soil profile site certainly influences their classification of the landform on which the profile is situated (aided by additional information such as topographic maps and aerial images). Variation of the L-value furthermore presents the opportunity to mimic the different scales at which surveyors describe soil profile locations. We first illustrate the use of r.geomorphon for site descriptions using exemplary artificial elevation profiles resembling typic catenas at different scales (L-values). We then compare the results of a landform element map computed with r.geomorphon to the relief descriptions in the test dataset. We link the surveyors' landform classification to the computed landform elements. Using a multi-scale approach we characterize raster cell locations in a way similar to the micro-, meso- and macroscale definitions used in soil survey, resulting in so-called geomorphon-signatures, such as "pit (meso-scale) located on a ridge (macro-scale)". We investigate which ranges of L-values best represent the different observation-scales as noted by soil surveyors and discuss the impacts of using a large dataset of profile location descriptions performed by different surveyors. Issues that arise are possible individual differences in landscape structure perception, but also questions regarding the accuracy of position and resulting topographic measurements in soil profile site description.

Onondaga Lake Inner Harbor Dredging Design Project, Syracuse, New York: Final Design Memorandum

DTIC Science & Technology

1997-06-01

sko «**’ D-l-12 AhmßMNN ’INTERNATIONAL I o s et H ) NOVAMANN (Ontario) ,nc, 5540 McAöam...SE COIIU I ISE ■s! z a: o UJ o < co~3E »3UZ Q.Ü UI 3 «- < O CO o a: u >- a at co o UJ m : a:’ 3 ««; = ’ o> I- • T- KO co < UJ UJ...a: en O z •t- KO UKUIU • or z 3>-z . </>•-■«- o l-< CJ UJ UJ < ZJ° «o CL Z o -o o >UJ sp«-< s; C/> t> UJ U CJ O f o <D

Repetitively Pulsed Electric Laser Acoustic Studies. Volume 1.

DTIC Science & Technology

1983-09-01

V a=[I (i/x)CS’]=I+HS’ b=CS1’ C:(z-iHwM)/(z- iwM )=H(x/i) S’=(1-S)/S. S=(D-d)/D=fraction open area of the attenuator. 67 ’-. -, .,"..-/ We note, that...the structure becomes • .’ ~u’:uz/(z- iwm ) (4.2)" where, as before, z=r-iwgHp and u is the average velocity ampli- tude of the gas in the porous...Again, making use of Eq. 4.2, these relations can be summarized as U. :C’u (4.4) pp-iwm1 C’u C’=z/(z- iwm ), z=r-iwgHp 5. Equations of motion. In terms of

Kangnung ROK AFS, K18, Korea. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

DTIC Science & Technology

1968-02-26

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Fracture and Viscoelastic Characteristics of the Human Cervical Spine,

DTIC Science & Technology

1986-01-01

to which the three hydraulic actuators are attached. Parameters ES and TS are input by the user to define the reference point T. The reference point T...S ILOLUS Z 𔃾 - - -~ -I-- :~ a I" eU ,. eS U wNiU ,’, -.. |-- • i *1 S U U, N. S S S S S U U a U S S 0 w * S ’I * & S * S Uz N* I p. z...a ’I 0m Me tno -$. satec Rotation (Psi. t~~5. P~i) O.T~a a1~ .~S lp 0 Angle I Max vert 2 Max hor:i d ’ (eg) range (mm) range (mm) I[@1 0 127 .00 330

Incorporating Information Value into Navy Tactical Data System: System Configuration Management Through the Delphi Method

DTIC Science & Technology

1989-03-01

e"-s tcc,: -e .- r reverse of necessary an., ice-tfy by bi.-:’ ru-’ce," 5uz"ou configuration management. Delphi method. Command and Control 19 Ac-s:’a...Aos!,ac: 21 Aostraczt Security Classitcator : R uncassf~’! i~e sa-e as renc- E 0orC users Unclassified 22a Na-e of Respon’s :e iro, v c a 22o Te’eo’one...i!r’ciule A’ea coce’ 22: C’" ce . Thomnas 1’. Mitchell (4081 646-2620 155k.11i DD FORI, 1473.6.: VAR 63 A-- R e-.!c- rnay be usec~ unti exhausted se

Strategies for modeling habitat relationships of uncommon species: An example using the Siskiyou Mountains salamander (Plethodon stormi).

Treesearch

Hartwell H. Welsh; Howard Stauffer; David R. Clayton; Lisa M. Ollivier

2007-01-01

We analyzed environmental relationships of the Siskiyou Mountains salamander, comparing attributes at the landscape, macro- and micro-environmental scales, and the three scales combined, to determine which attributes best predicted salamander presence. Separate analyses were conducted for sites on the north and south sides of the Siskiyou Mountains which basically...

Net nitrogen mineralization in natural ecosystems across the conterminous US

Treesearch

LeeAnna Y. Chapman; Steven G. McNulty; Ge Sun; Yang Zhang

2013-01-01

Nitrogen is the primary nutrient limiting ecosystem productivity over most of the US. Although soil nitrogen content is important, knowledge about its spatial extent at the continental scale is limited. The objective of this study was to estimate net nitrogen mineralization for the conterminous US (CONUS) using an empirical modeling approach by scaling up site level...

Irreversible opinion spreading on scale-free networks

NASA Astrophysics Data System (ADS)

Candia, Julián

2007-02-01

We study the dynamical and critical behavior of a model for irreversible opinion spreading on Barabási-Albert (BA) scale-free networks by performing extensive Monte Carlo simulations. The opinion spreading within an inhomogeneous society is investigated by means of the magnetic Eden model, a nonequilibrium kinetic model for the growth of binary mixtures in contact with a thermal bath. The deposition dynamics, which is studied as a function of the degree of the occupied sites, shows evidence for the leading role played by hubs in the growth process. Systems of finite size grow either ordered or disordered, depending on the temperature. By means of standard finite-size scaling procedures, the effective order-disorder phase transitions are found to persist in the thermodynamic limit. This critical behavior, however, is absent in related equilibrium spin systems such as the Ising model on BA scale-free networks, which in the thermodynamic limit only displays a ferromagnetic phase. The dependence of these results on the degree exponent is also discussed for the case of uncorrelated scale-free networks.

Building a sense of virtual community: the role of the features of social networking sites.

PubMed

Chen, Chi-Wen; Lin, Chiun-Sin

2014-07-01

In recent years, social networking sites have received increased attention because of the potential of this medium to transform business by building virtual communities. However, theoretical and empirical studies investigating how specific features of social networking sites contribute to building a sense of virtual community (SOVC)-an important dimension of a successful virtual community-are rare. Furthermore, SOVC scales have been developed, and research on this issue has been called for, but few studies have heeded this call. On the basis of prior literature, this study proposes that perceptions of the three most salient features of social networking sites-system quality (SQ), information quality (IQ), and social information exchange (SIE)-play a key role in fostering SOVC. In particular, SQ is proposed to increase IQ and SIE, and SIE is proposed to enhance IQ, both of which thereafter build SOVC. The research model was examined in the context of Facebook, one of the most popular social networking sites in the world. We adopted Blanchard's scales to measure SOVC. Data gathered using a Web-based questionnaire, and analyzed with partial least squares, were utilized to test the model. The results demonstrate that SIE, SQ, and IQ are the factors that form SOVC. The findings also suggest that SQ plays a fundamental role in supporting SIE and IQ in social networking sites. Implications for theory, practice, and future research directions are discussed.

Intelligent Facades for High Performance Green Buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyson, Anna

Progress Towards Net-Zero and Net-Positive-Energy Commercial Buildings and Urban Districts Through Intelligent Building Envelope Strategies Previous research and development of intelligent facades systems has been limited in their contribution towards national goals for achieving on-site net zero buildings, because this R&D has failed to couple the many qualitative requirements of building envelopes such as the provision of daylighting, access to exterior views, satisfying aesthetic and cultural characteristics, with the quantitative metrics of energy harvesting, storage and redistribution. To achieve energy self-sufficiency from on-site solar resources, building envelopes can and must address this gamut of concerns simultaneously. With this project, wemore » have undertaken a high-performance building integrated combined-heat and power concentrating photovoltaic system with high temperature thermal capture, storage and transport towards multiple applications (BICPV/T). The critical contribution we are offering with the Integrated Concentrating Solar Façade (ICSF) is conceived to improve daylighting quality for improved health of occupants and mitigate solar heat gain while maximally capturing and transferring onsite solar energy. The ICSF accomplishes this multi-functionality by intercepting only the direct-normal component of solar energy (which is responsible for elevated cooling loads) thereby transforming a previously problematic source of energy into a high quality resource that can be applied to building demands such as heating, cooling, dehumidification, domestic hot water, and possible further augmentation of electrical generation through organic Rankine cycles. With the ICSF technology, our team is addressing the global challenge in transitioning commercial and residential building stock towards on-site clean energy self-sufficiency, by fully integrating innovative environmental control systems strategies within an intelligent and responsively dynamic building envelope. The advantage of being able to use the entire solar spectrum for active and passive benefits, along with the potential savings of avoiding transmission losses through direct current (DC) transfer to all buildings systems directly from the site of solar conversion, gives the system a compounded economic viability within the commercial and institutional building markets. With a team that spans multiple stakeholders across disparate industries, from CPV to A&E partners that are responsible for the design and development of District and Regional Scale Urban Development, this project demonstrates that integrating utility-scale high efficiency CPV installations with urban and suburban environments is both viable and desirable within the marketplace. The historical schism between utility scale CPV and BIPV has been one of differing scale and cultures. There is no technical reason why utility-scale CPV cannot be located within urban embedded district scale sites of energy harvesting. New models for leasing large areas of district scale roofs and facades are emerging, such that the model for utility scale energy harvesting can be reconciled to commercial and public scale building sites and campuses. This consortium is designed to unite utility scale solar harvesting into building applications for smart grid development.« less

Uranium plume persistence impacted by hydrologic and geochemical heterogeneity in the groundwater and river water interaction zone of Hanford site

NASA Astrophysics Data System (ADS)

Chen, X.; Zachara, J. M.; Vermeul, V. R.; Freshley, M.; Hammond, G. E.

2015-12-01

The behavior of a persistent uranium plume in an extended groundwater- river water (GW-SW) interaction zone at the DOE Hanford site is dominantly controlled by river stage fluctuations in the adjacent Columbia River. The plume behavior is further complicated by substantial heterogeneity in physical and geochemical properties of the host aquifer sediments. Multi-scale field and laboratory experiments and reactive transport modeling were integrated to understand the complex plume behavior influenced by highly variable hydrologic and geochemical conditions in time and space. In this presentation we (1) describe multiple data sets from field-scale uranium adsorption and desorption experiments performed at our experimental well-field, (2) develop a reactive transport model that incorporates hydrologic and geochemical heterogeneities characterized from multi-scale and multi-type datasets and a surface complexation reaction network based on laboratory studies, and (3) compare the modeling and observation results to provide insights on how to refine the conceptual model and reduce prediction uncertainties. The experimental results revealed significant spatial variability in uranium adsorption/desorption behavior, while modeling demonstrated that ambient hydrologic and geochemical conditions and heterogeneities in sediment physical and chemical properties both contributed to complex plume behavior and its persistence. Our analysis provides important insights into the characterization, understanding, modeling, and remediation of groundwater contaminant plumes influenced by surface water and groundwater interactions.

Analytical study of nano-scale logical operations

NASA Astrophysics Data System (ADS)

Patra, Moumita; Maiti, Santanu K.

2018-07-01

A complete analytical prescription is given to perform three basic (OR, AND, NOT) and two universal (NAND, NOR) logic gates at nano-scale level using simple tailor made geometries. Two different geometries, ring-like and chain-like, are taken into account where in each case the bridging conductor is coupled to a local atomic site through a dangling bond whose site energy can be controlled by means of external gate electrode. The main idea is that when injecting electron energy matches with site energy of local atomic site transmission probability drops exactly to zero, whereas the junction exhibits finite transmission for other energies. Utilizing this prescription we perform logical operations, and, we strongly believe that the proposed results can be verified in laboratory. Finally, we numerically compute two-terminal transmission probability considering general models and the numerical results match exactly well with our analytical findings.

Agricultural disturbance response models for invertebrate and algal metrics from streams at two spatial scales within the U.S.

USGS Publications Warehouse

Waite, Ian R.

2014-01-01

As part of the USGS study of nutrient enrichment of streams in agricultural regions throughout the United States, about 30 sites within each of eight study areas were selected to capture a gradient of nutrient conditions. The objective was to develop watershed disturbance predictive models for macroinvertebrate and algal metrics at national and three regional landscape scales to obtain a better understanding of important explanatory variables. Explanatory variables in models were generated from landscape data, habitat, and chemistry. Instream nutrient concentration and variables assessing the amount of disturbance to the riparian zone (e.g., percent row crops or percent agriculture) were selected as most important explanatory variable in almost all boosted regression tree models regardless of landscape scale or assemblage. Frequently, TN and TP concentration and riparian agricultural land use variables showed a threshold type response at relatively low values to biotic metrics modeled. Some measure of habitat condition was also commonly selected in the final invertebrate models, though the variable(s) varied across regions. Results suggest national models tended to account for more general landscape/climate differences, while regional models incorporated both broad landscape scale and more specific local-scale variables.

Field investigation of the drift shadow

USGS Publications Warehouse

Su, G.W.; Kneafsey, T.J.; Ghezzehei, T.A.; Cook, P.J.; Marshall, B.D.

2006-01-01

The "Drift Shadow" is defined as the relatively drier region that forms below subsurface cavities or drifts in unsaturated rock. Its existence has been predicted through analytical and numerical models of unsaturated flow. However, these theoretical predictions have not been demonstrated empirically to date. In this project we plan to test the drift shadow concept through field investigations and compare our observations to simulations. Based on modeling studies we have an identified a suitable site to perform the study at an inactive mine in a sandstone formation. Pretest modeling studies and preliminary characterization of the site are being used to develop the field scale tests.

Event-based total suspended sediment particle size distribution model

NASA Astrophysics Data System (ADS)

Thompson, Jennifer; Sattar, Ahmed M. A.; Gharabaghi, Bahram; Warner, Richard C.

2016-05-01

One of the most challenging modelling tasks in hydrology is prediction of the total suspended sediment particle size distribution (TSS-PSD) in stormwater runoff generated from exposed soil surfaces at active construction sites and surface mining operations. The main objective of this study is to employ gene expression programming (GEP) and artificial neural networks (ANN) to develop a new model with the ability to more accurately predict the TSS-PSD by taking advantage of both event-specific and site-specific factors in the model. To compile the data for this study, laboratory scale experiments using rainfall simulators were conducted on fourteen different soils to obtain TSS-PSD. This data is supplemented with field data from three construction sites in Ontario over a period of two years to capture the effect of transport and deposition within the site. The combined data sets provide a wide range of key overlooked site-specific and storm event-specific factors. Both parent soil and TSS-PSD in runoff are quantified by fitting each to a lognormal distribution. Compared to existing regression models, the developed model more accurately predicted the TSS-PSD using a more comprehensive list of key model input parameters. Employment of the new model will increase the efficiency of deployment of required best management practices, designed based on TSS-PSD, to minimize potential adverse effects of construction site runoff on aquatic life in the receiving watercourses.

Small Scale Irrigation within Water, Energy and Food Nexus Framework in Ethiopia.

NASA Astrophysics Data System (ADS)

Gerik, T.; Worqlul, A. W.; Yihun, D.; Bizimana, J. C.; Jeong, J.; Schmitter, P.; Srinivasan, R.; Richardson, J. W.; Clark, N.

2017-12-01

This study presents the nexus of food, energy and water framework in the context of small scale irrigation for vegetable production during the dry season in an irrigated agriculture system in Ethiopia. The study is based on detailed data collected in three sites of the Innovation Lab for Small Scale Irrigation (ILSSI) project in Ethiopia. The sites were Robit, Dangishta and Lemo and detailed field data was collected in 18 households in each site. The field data collected includes crop management (such as irrigation amount and dates, fertilizer rates, tillage practices, irrigation technologies, etc.) and agricultural production (crop yield, biomass, etc.) on tomato, onion and cabbage during the dry season. Four different water lifting technologies - namely rope with pulley and bucket, rope and washer pump, solar pump and motor pump - were used for water withdrawal from shallow groundwater wells. The Soil and Water Assessment Tool (SWAT) and Agricultural Policy Environmental eXtender (APEX) models were used in an integrated manner to assess water resource potential and develop water use efficiency of vegetables, which is a relationship between amount of water applied and vegetable yield. The water use efficiency for each vegetable crops were translated into energy requirement as pumping hours and potential irrigable areas for the water lifting technologies. This integrated approach was found useful to optimize water and energy use for sustainable food production using small scale irrigation. The holistic approach will not only provide a significant contribution to achieving food self-sufficiency, but will also be effective for optimizing agricultural input. Keyword: small scale irrigation, integrated modeling, water lifting technology, East Africa

Show me the data: advances in multi-model benchmarking, assimilation, and forecasting

NASA Astrophysics Data System (ADS)

Dietze, M.; Raiho, A.; Fer, I.; Cowdery, E.; Kooper, R.; Kelly, R.; Shiklomanov, A. N.; Desai, A. R.; Simkins, J.; Gardella, A.; Serbin, S.

2016-12-01

Researchers want their data to inform carbon cycle predictions, but there are considerable bottlenecks between data collection and the use of data to calibrate and validate earth system models and inform predictions. This talk highlights recent advancements in the PEcAn project aimed at it making it easier for individual researchers to confront models with their own data: (1) The development of an easily extensible site-scale benchmarking system aimed at ensuring that models capture process rather than just reproducing pattern; (2) Efficient emulator-based Bayesian parameter data assimilation to constrain model parameters; (3) A novel, generalized approach to ensemble data assimilation to estimate carbon pools and fluxes and quantify process error; (4) automated processing and downscaling of CMIP climate scenarios to support forecasts that include driver uncertainty; (5) a large expansion in the number of models supported, with new tools for conducting multi-model and multi-site analyses; and (6) a network-based architecture that allows analyses to be shared with model developers and other collaborators. Application of these methods is illustrated with data across a wide range of time scales, from eddy-covariance to forest inventories to tree rings to paleoecological pollen proxies.

Using sensitivity analysis in model calibration efforts

USGS Publications Warehouse

Tiedeman, Claire; Hill, Mary C.

2003-01-01

In models of natural and engineered systems, sensitivity analysis can be used to assess relations among system state observations, model parameters, and model predictions. The model itself links these three entities, and model sensitivities can be used to quantify the links. Sensitivities are defined as the derivatives of simulated quantities (such as simulated equivalents of observations, or model predictions) with respect to model parameters. We present four measures calculated from model sensitivities that quantify the observation-parameter-prediction links and that are especially useful during the calibration and prediction phases of modeling. These four measures are composite scaled sensitivities (CSS), prediction scaled sensitivities (PSS), the value of improved information (VOII) statistic, and the observation prediction (OPR) statistic. These measures can be used to help guide initial calibration of models, collection of field data beneficial to model predictions, and recalibration of models updated with new field information. Once model sensitivities have been calculated, each of the four measures requires minimal computational effort. We apply the four measures to a three-layer MODFLOW-2000 (Harbaugh et al., 2000; Hill et al., 2000) model of the Death Valley regional ground-water flow system (DVRFS), located in southern Nevada and California. D’Agnese et al. (1997, 1999) developed and calibrated the model using nonlinear regression methods. Figure 1 shows some of the observations, parameters, and predictions for the DVRFS model. Observed quantities include hydraulic heads and spring flows. The 23 defined model parameters include hydraulic conductivities, vertical anisotropies, recharge rates, evapotranspiration rates, and pumpage. Predictions of interest for this regional-scale model are advective transport paths from potential contamination sites underlying the Nevada Test Site and Yucca Mountain.

Topographic Metric Predictions of Soil redistribution and Organic Carbon Distribution in Croplands

NASA Astrophysics Data System (ADS)

Mccarty, G.; Li, X.

2017-12-01

Landscape topography is a key factor controlling soil redistribution and soil organic carbon (SOC) distribution in Iowa croplands (USA). In this study, we adopted a combined approach based on carbon () and cesium (137Cs) isotope tracers, and digital terrain analysis to understand patterns of SOC redistribution and carbon sequestration dynamics as influenced by landscape topography in tilled cropland under long term corn/soybean management. The fallout radionuclide 137Cs was used to estimate soil redistribution rates and a Lidar-derived DEM was used to obtain a set of topographic metrics for digital terrain analysis. Soil redistribution rates and patterns of SOC distribution were examined across 560 sampling locations at two field sites as well as at larger scale within the watershed. We used δ13C content in SOC to partition C3 and C4 plant derived C density at 127 locations in one of the two field sites with corn being the primary source of C4 C. Topography-based models were developed to simulate SOC distribution and soil redistribution using stepwise ordinary least square regression (SOLSR) and stepwise principal component regression (SPCR). All topography-based models developed through SPCR and SOLSR demonstrated good simulation performance, explaining more than 62% variability in SOC density and soil redistribution rates across two field sites with intensive samplings. However, the SOLSR models showed lower reliability than the SPCR models in predicting SOC density at the watershed scale. Spatial patterns of C3-derived SOC density were highly related to those of SOC density. Topographic metrics exerted substantial influence on C3-derived SOC density with the SPCR model accounting for 76.5% of the spatial variance. In contrast C4 derived SOC density had poor spatial structure likely reflecting the substantial contribution of corn vegetation to recently sequestered SOC density. Results of this study highlighted the utility of topographic SPCR models for scaling field measurements of SOC density and soil redistribution rates to watershed scale which will allow watershed model to better predict fate of ecosystem C on agricultural landscapes.

Large-scale monitoring of shorebird populations using count data and N-mixture models: Black Oystercatcher (Haematopus bachmani) surveys by land and sea

USGS Publications Warehouse

Lyons, James E.; Andrew, Royle J.; Thomas, Susan M.; Elliott-Smith, Elise; Evenson, Joseph R.; Kelly, Elizabeth G.; Milner, Ruth L.; Nysewander, David R.; Andres, Brad A.

2012-01-01

Large-scale monitoring of bird populations is often based on count data collected across spatial scales that may include multiple physiographic regions and habitat types. Monitoring at large spatial scales may require multiple survey platforms (e.g., from boats and land when monitoring coastal species) and multiple survey methods. It becomes especially important to explicitly account for detection probability when analyzing count data that have been collected using multiple survey platforms or methods. We evaluated a new analytical framework, N-mixture models, to estimate actual abundance while accounting for multiple detection biases. During May 2006, we made repeated counts of Black Oystercatchers (Haematopus bachmani) from boats in the Puget Sound area of Washington (n = 55 sites) and from land along the coast of Oregon (n = 56 sites). We used a Bayesian analysis of N-mixture models to (1) assess detection probability as a function of environmental and survey covariates and (2) estimate total Black Oystercatcher abundance during the breeding season in the two regions. Probability of detecting individuals during boat-based surveys was 0.75 (95% credible interval: 0.42–0.91) and was not influenced by tidal stage. Detection probability from surveys conducted on foot was 0.68 (0.39–0.90); the latter was not influenced by fog, wind, or number of observers but was ~35% lower during rain. The estimated population size was 321 birds (262–511) in Washington and 311 (276–382) in Oregon. N-mixture models provide a flexible framework for modeling count data and covariates in large-scale bird monitoring programs designed to understand population change.

Parameterizing atmosphere-land surface exchange for climate models with satellite data: A case study for the Southern Great Plains CART site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, W.

High-resolution satellite data provide detailed, quantitative descriptions of land surface characteristics over large areas so that objective scale linkage becomes feasible. With the aid of satellite data, Sellers et al. and Wood and Lakshmi examined the linearity of processes scaled up from 30 m to 15 km. If the phenomenon is scale invariant, then the aggregated value of a function or flux is equivalent to the function computed from aggregated values of controlling variables. The linear relation may be realistic for limited land areas having no large surface contrasts to cause significant horizontal exchange. However, for areas with sharp surfacemore » contrasts, horizontal exchange and different dynamics in the atmospheric boundary may induce nonlinear interactions, such as at interfaces of land-water, forest-farm land, and irrigated crops-desert steppe. The linear approach, however, represents the simplest scenario, and is useful for developing an effective scheme for incorporating subgrid land surface processes into large-scale models. Our studies focus on coupling satellite data and ground measurements with a satellite-data-driven land surface model to parameterize surface fluxes for large-scale climate models. In this case study, we used surface spectral reflectance data from satellite remote sensing to characterize spatial and temporal changes in vegetation and associated surface parameters in an area of about 350 {times} 400 km covering the southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site of the US Department of Energy`s Atmospheric Radiation Measurement (ARM) Program.« less

Silvicolous on a small scale: possibilities and limitations of habitat suitability models for small, elusive mammals in conservation management and landscape planning.

PubMed

Becker, Nina I; Encarnação, Jorge A

2015-01-01

Species distribution and endangerment can be assessed by habitat-suitability modelling. This study addresses methodical aspects of habitat suitability modelling and includes an application example in actual species conservation and landscape planning. Models using species presence-absence data are preferable to presence-only models. In contrast to species presence data, absences are rarely recorded. Therefore, many studies generate pseudo-absence data for modelling. However, in this study model quality was higher with null samples collected in the field. Next to species data the choice of landscape data is crucial for suitability modelling. Landscape data with high resolution and ecological relevance for the study species improve model reliability and quality for small elusive mammals like Muscardinus avellanarius. For large scale assessment of species distribution, models with low-detailed data are sufficient. For regional site-specific conservation issues like a conflict-free site for new wind turbines, high-detailed regional models are needed. Even though the overlap with optimally suitable habitat for M. avellanarius was low, the installation of wind plants can pose a threat due to habitat loss and fragmentation. To conclude, modellers should clearly state the purpose of their models and choose the according level of detail for species and environmental data.

Identifiability in N-mixture models: a large-scale screening test with bird data.

PubMed

Kéry, Marc

2018-02-01

Binomial N-mixture models have proven very useful in ecology, conservation, and monitoring: they allow estimation and modeling of abundance separately from detection probability using simple counts. Recently, doubts about parameter identifiability have been voiced. I conducted a large-scale screening test with 137 bird data sets from 2,037 sites. I found virtually no identifiability problems for Poisson and zero-inflated Poisson (ZIP) binomial N-mixture models, but negative-binomial (NB) models had problems in 25% of all data sets. The corresponding multinomial N-mixture models had no problems. Parameter estimates under Poisson and ZIP binomial and multinomial N-mixture models were extremely similar. Identifiability problems became a little more frequent with smaller sample sizes (267 and 50 sites), but were unaffected by whether the models did or did not include covariates. Hence, binomial N-mixture model parameters with Poisson and ZIP mixtures typically appeared identifiable. In contrast, NB mixtures were often unidentifiable, which is worrying since these were often selected by Akaike's information criterion. Identifiability of binomial N-mixture models should always be checked. If problems are found, simpler models, integrated models that combine different observation models or the use of external information via informative priors or penalized likelihoods, may help. © 2017 by the Ecological Society of America.

Silvicolous on a Small Scale: Possibilities and Limitations of Habitat Suitability Models for Small, Elusive Mammals in Conservation Management and Landscape Planning

PubMed Central

2015-01-01

Species distribution and endangerment can be assessed by habitat-suitability modelling. This study addresses methodical aspects of habitat suitability modelling and includes an application example in actual species conservation and landscape planning. Models using species presence-absence data are preferable to presence-only models. In contrast to species presence data, absences are rarely recorded. Therefore, many studies generate pseudo-absence data for modelling. However, in this study model quality was higher with null samples collected in the field. Next to species data the choice of landscape data is crucial for suitability modelling. Landscape data with high resolution and ecological relevance for the study species improve model reliability and quality for small elusive mammals like Muscardinus avellanarius. For large scale assessment of species distribution, models with low-detailed data are sufficient. For regional site-specific conservation issues like a conflict-free site for new wind turbines, high-detailed regional models are needed. Even though the overlap with optimally suitable habitat for M. avellanarius was low, the installation of wind plants can pose a threat due to habitat loss and fragmentation. To conclude, modellers should clearly state the purpose of their models and choose the according level of detail for species and environmental data. PMID:25781894

Monitoring and assessment of soil erosion at micro-scale and macro-scale in forests affected by fire damage in northern Iran.

PubMed

Akbarzadeh, Ali; Ghorbani-Dashtaki, Shoja; Naderi-Khorasgani, Mehdi; Kerry, Ruth; Taghizadeh-Mehrjardi, Ruhollah

2016-12-01

Understanding the occurrence of erosion processes at large scales is very difficult without studying them at small scales. In this study, soil erosion parameters were investigated at micro-scale and macro-scale in forests in northern Iran. Surface erosion and some vegetation attributes were measured at the watershed scale in 30 parcels of land which were separated into 15 fire-affected (burned) forests and 15 original (unburned) forests adjacent to the burned sites. The soil erodibility factor and splash erosion were also determined at the micro-plot scale within each burned and unburned site. Furthermore, soil sampling and infiltration studies were carried out at 80 other sites, as well as the 30 burned and unburned sites, (a total of 110 points) to create a map of the soil erodibility factor at the regional scale. Maps of topography, rainfall, and cover-management were also determined for the study area. The maps of erosion risk and erosion risk potential were finally prepared for the study area using the Revised Universal Soil Loss Equation (RUSLE) procedure. Results indicated that destruction of the protective cover of forested areas by fire had significant effects on splash erosion and the soil erodibility factor at the micro-plot scale and also on surface erosion, erosion risk, and erosion risk potential at the watershed scale. Moreover, the results showed that correlation coefficients between different variables at the micro-plot and watershed scales were positive and significant. Finally, assessment and monitoring of the erosion maps at the regional scale showed that the central and western parts of the study area were more susceptible to erosion compared with the western regions due to more intense crop-management, greater soil erodibility, and more rainfall. The relationships between erosion parameters and the most important vegetation attributes were also used to provide models with equations that were specific to the study region. The results of this paper can be useful for better understanding erosion processes at the micro-scale and macro-scale in any region having similar vegetation attributes to the forests of northern Iran.

Field investigation into unsaturated flow and transport in a fault: Model analyses

USGS Publications Warehouse

Liu, H.-H.; Salve, R.; Wang, J.-S.; Bodvarsson, G.S.; Hudson, D.

2004-01-01

Results of a fault test performed in the unsaturated zone of Yucca Mountain, Nevada, were analyzed using a three-dimensional numerical model. The fault was explicitly represented as a discrete feature and the surrounding rock was treated as a dual-continuum (fracture-matrix) system. Model calibration against seepage and water-travel-velocity data suggests that lithophysal cavities connected to fractures can considerably enhance the effective fracture porosity and therefore retard water flow in fractures. Comparisons between simulation results and tracer concentration data also indicate that matrix diffusion is an important mechanism for solute transport in unsaturated fractured rock. We found that an increased fault-matrix and fracture-matrix interface areas were needed to match the observed tracer data, which is consistent with previous studies. The study results suggest that the current site-scale model for the unsaturated zone of Yucca Mountain may underestimate radionuclide transport time within the unsaturated zone, because an increased fracture-matrix interface area and the increased effective fracture porosity arising from lithophysal cavities are not considered in the current site-scale model. ?? 2004 Published by Elsevier B.V.

Plant traits, productivity, biomass and soil properties from forest sites in the Pacific Northwest, 1999-2014.

PubMed

Berner, Logan T; Law, Beverly E

2016-01-19

Plant trait measurements are needed for evaluating ecological responses to environmental conditions and for ecosystem process model development, parameterization, and testing. We present a standardized dataset integrating measurements from projects conducted by the Terrestrial Ecosystem Research and Regional Analysis- Pacific Northwest (TERRA-PNW) research group between 1999 and 2014 across Oregon and Northern California, where measurements were collected for scaling and modeling regional terrestrial carbon processes with models such as Biome-BGC and the Community Land Model. The dataset contains measurements of specific leaf area, leaf longevity, leaf carbon and nitrogen for 35 tree and shrub species derived from more than 1,200 branch samples collected from over 200 forest plots, including several AmeriFlux sites. The dataset also contains plot-level measurements of forest composition, structure (e.g., tree biomass), and productivity, as well as measurements of soil structure (e.g., bulk density) and chemistry (e.g., carbon). Publically-archiving regional datasets of standardized, co-located, and geo-referenced plant trait measurements will advance the ability of earth system models to capture species-level climate sensitivity at regional to global scales.

Plant traits, productivity, biomass and soil properties from forest sites in the Pacific Northwest, 1999-2014

NASA Astrophysics Data System (ADS)

Berner, Logan T.; Law, Beverly E.

2016-01-01

Plant trait measurements are needed for evaluating ecological responses to environmental conditions and for ecosystem process model development, parameterization, and testing. We present a standardized dataset integrating measurements from projects conducted by the Terrestrial Ecosystem Research and Regional Analysis- Pacific Northwest (TERRA-PNW) research group between 1999 and 2014 across Oregon and Northern California, where measurements were collected for scaling and modeling regional terrestrial carbon processes with models such as Biome-BGC and the Community Land Model. The dataset contains measurements of specific leaf area, leaf longevity, leaf carbon and nitrogen for 35 tree and shrub species derived from more than 1,200 branch samples collected from over 200 forest plots, including several AmeriFlux sites. The dataset also contains plot-level measurements of forest composition, structure (e.g., tree biomass), and productivity, as well as measurements of soil structure (e.g., bulk density) and chemistry (e.g., carbon). Publically-archiving regional datasets of standardized, co-located, and geo-referenced plant trait measurements will advance the ability of earth system models to capture species-level climate sensitivity at regional to global scales.

The importance of radiation for semiempirical water-use efficiency models

DOE PAGES

Boese, Sven; Jung, Martin; Carvalhais, Nuno; ...

2017-06-22

Water-use efficiency (WUE) is a fundamental property for the coupling of carbon and water cycles in plants and ecosystems. Existing model formulations predicting this variable differ in the type of response of WUE to the atmospheric vapor pressure deficit of water (VPD). We tested a representative WUE model on the ecosystem scale at 110 eddy covariance sites of the FLUXNET initiative by predicting evapotranspiration (ET) based on gross primary productivity (GPP) and VPD. We found that introducing an intercept term in the formulation increases model performance considerably, indicating that an additional factor needs to be considered. We demonstrate that thismore » intercept term varies seasonally and we subsequently associate it with radiation. Replacing the constant intercept term with a linear function of global radiation was found to further improve model predictions of ET. Our new semiempirical ecosystem WUE formulation indicates that, averaged over all sites, this radiation term accounts for up to half (39–47 %) of transpiration. These empirical findings challenge the current understanding of water-use efficiency on the ecosystem scale.« less

Innovative mathematical modeling in environmental remediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeh, Gour T.; National Central Univ.; Univ. of Central Florida

2013-05-01

There are two different ways to model reactive transport: ad hoc and innovative reaction-based approaches. The former, such as the Kd simplification of adsorption, has been widely employed by practitioners, while the latter has been mainly used in scientific communities for elucidating mechanisms of biogeochemical transport processes. It is believed that innovative mechanistic-based models could serve as protocols for environmental remediation as well. This paper reviews the development of a mechanistically coupled fluid flow, thermal transport, hydrologic transport, and reactive biogeochemical model and example-applications to environmental remediation problems. Theoretical bases are sufficiently described. Four example problems previously carried out aremore » used to demonstrate how numerical experimentation can be used to evaluate the feasibility of different remediation approaches. The first one involved the application of a 56-species uranium tailing problem to the Melton Branch Subwatershed at Oak Ridge National Laboratory (ORNL) using the parallel version of the model. Simulations were made to demonstrate the potential mobilization of uranium and other chelating agents in the proposed waste disposal site. The second problem simulated laboratory-scale system to investigate the role of natural attenuation in potential off-site migration of uranium from uranium mill tailings after restoration. It showed inadequacy of using a single Kd even for a homogeneous medium. The third example simulated laboratory experiments involving extremely high concentrations of uranium, technetium, aluminum, nitrate, and toxic metals (e.g.,Ni, Cr, Co).The fourth example modeled microbially-mediated immobilization of uranium in an unconfined aquifer using acetate amendment in a field-scale experiment. The purposes of these modeling studies were to simulate various mechanisms of mobilization and immobilization of radioactive wastes and to illustrate how to apply reactive transport models for environmental remediation.The second problem simulated laboratory-scale system to investigate the role of natural attenuation in potential off-site migration of uranium from uranium mill tailings after restoration. It showed inadequacy of using a single Kd even for a homogeneous medium.« less

Effect of small versus large clusters of fish school on the yield of a purse-seine small pelagic fishery including a marine protected area.

PubMed

Hieu, Nguyen Trong; Brochier, Timothée; Tri, Nguyen-Huu; Auger, Pierre; Brehmer, Patrice

2014-09-01

We consider a fishery model with two sites: (1) a marine protected area (MPA) where fishing is prohibited and (2) an area where the fish population is harvested. We assume that fish can migrate from MPA to fishing area at a very fast time scale and fish spatial organisation can change from small to large clusters of school at a fast time scale. The growth of the fish population and the catch are assumed to occur at a slow time scale. The complete model is a system of five ordinary differential equations with three time scales. We take advantage of the time scales using aggregation of variables methods to derive a reduced model governing the total fish density and fishing effort at the slow time scale. We analyze this aggregated model and show that under some conditions, there exists an equilibrium corresponding to a sustainable fishery. Our results suggest that in small pelagic fisheries the yield is maximum for a fish population distributed among both small and large clusters of school.

An optimal beam alignment method for large-scale distributed space surveillance radar system

NASA Astrophysics Data System (ADS)

Huang, Jian; Wang, Dongya; Xia, Shuangzhi

2018-06-01

Large-scale distributed space surveillance radar is a very important ground-based equipment to maintain a complete catalogue for Low Earth Orbit (LEO) space debris. However, due to the thousands of kilometers distance between each sites of the distributed radar system, how to optimally implement the Transmitting/Receiving (T/R) beams alignment in a great space using the narrow beam, which proposed a special and considerable technical challenge in the space surveillance area. According to the common coordinate transformation model and the radar beam space model, we presented a two dimensional projection algorithm for T/R beam using the direction angles, which could visually describe and assess the beam alignment performance. Subsequently, the optimal mathematical models for the orientation angle of the antenna array, the site location and the T/R beam coverage are constructed, and also the beam alignment parameters are precisely solved. At last, we conducted the optimal beam alignment experiments base on the site parameters of Air Force Space Surveillance System (AFSSS). The simulation results demonstrate the correctness and effectiveness of our novel method, which can significantly stimulate the construction for the LEO space debris surveillance equipment.

Estimation of Regional Net CO2 Exchange over the Southern Great Plains

NASA Astrophysics Data System (ADS)

Biraud, S. C.; Riley, W. J.; Fischer, M. L.; Torn, M. S.; Cooley, H. S.

2004-12-01

Estimating spatially distributed ecosystem CO2 exchange is an important component of the North American Carbon Program. We describe here a methodology to estimate Net Ecosystem Exchange (NEE) over the Southern Great Plains, using: (1) data from the Department Of Energy's Atmospheric Radiation Measurement (ARM) sites in Oklahoma and Kansas; (2) meteorological forcing data from the Mesonet facilities; (3) soil and vegetation types from 1 km resolution USGS databases; (4) vegetation status (e.g., LAI) from 1 km satellite measurements of surface reflectance (MODIS); (5) a tested land-surface model; and (6) a coupled land-surface and meteorological model (MM5/ISOLSM). This framework allows us to simulate regional surface fluxes in addition to ABL and free troposphere concentrations of CO2 at a continental scale with fine-scale nested grids centered on the ARM central facility. We use the offline land-surface and coupled models to estimate regional NEE, and compare predictions to measurements from the 9 Extended Facility sites with eddy correlation measurements. Site level comparisons to portable ECOR measurements in several crop types are also presented. Our approach also allows us to extend bottom-up estimates to periods and areas where meteorological forcing data are unavailable.

Assessing allometric models to predict vegetative growth of mango (Mangifera indica; Anacardiaceae) at the current-year branch scale.

PubMed

Normand, Frédéric; Lauri, Pierre-Éric

2012-03-01

Accurate and reliable predictive models are necessary to estimate nondestructively key variables for plant growth studies such as leaf area and leaf, stem, and total biomass. Predictive models are lacking at the current-year branch scale despite the importance of this scale in plant science. We calibrated allometric models to estimate leaf area and stem and branch (leaves + stem) mass of current-year branches, i.e., branches several months old studied at the end of the vegetative growth season, of four mango cultivars on the basis of their basal cross-sectional area. The effects of year, site, and cultivar were tested. Models were validated with independent data and prediction accuracy was evaluated with the appropriate statistics. Models revealed a positive allometry between dependent and independent variables, whose y-intercept but not the slope, was affected by the cultivar. The effects of year and site were negligible. For each branch characteristic, cultivar-specific models were more accurate than common models built with pooled data from the four cultivars. Prediction quality was satisfactory but with data dispersion around the models, particularly for large values. Leaf area and stem and branch mass of mango current-year branches could be satisfactorily estimated on the basis of branch basal cross-sectional area with cultivar-specific allometric models. The results suggested that, in addition to the heteroscedastic behavior of the variables studied, model accuracy was probably related to the functional plasticity of branches in relation to the light environment and/or to the number of growth units composing the branches.

Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices

NASA Astrophysics Data System (ADS)

Reichstein, Markus; Rey, Ana; Freibauer, Annette; Tenhunen, John; Valentini, Riccardo; Banza, Joao; Casals, Pere; Cheng, Yufu; Grünzweig, Jose M.; Irvine, James; Joffre, Richard; Law, Beverly E.; Loustau, Denis; Miglietta, Franco; Oechel, Walter; Ourcival, Jean-Marc; Pereira, Joao S.; Peressotti, Alessandro; Ponti, Francesca; Qi, Ye; Rambal, Serge; Rayment, Mark; Romanya, Joan; Rossi, Federica; Tedeschi, Vanessa; Tirone, Giampiero; Xu, Ming; Yakir, Dan

2003-12-01

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g., leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical nonlinear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content, and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and intersite variability of soil respiration with a mean absolute error of 0.82 μmol m-2 s-1. The parameterized model exhibits the following principal properties: (1) At a relative amount of upper-layer soil water of 16% of field capacity, half-maximal soil respiration rates are reached. (2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. (3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly timescale, we employed the approach by [2002] that used monthly precipitation and air temperature to globally predict soil respiration (T&P model). While this model was able to explain some of the month-to-month variability of soil respiration, it failed to capture the intersite variability, regardless of whether the original or a new optimized model parameterization was used. In both cases, the residuals were strongly related to maximum site leaf area index. Thus, for a monthly timescale, we developed a simple T&P&LAI model that includes leaf area index as an additional predictor of soil respiration. This extended but still simple model performed nearly as well as the more detailed time step model and explained 50% of the overall and 65% of the site-to-site variability. Consequently, better estimates of globally distributed soil respiration should be obtained with the new model driven by satellite estimates of leaf area index. Before application at the continental or global scale, this approach should be further tested in boreal, cold-temperate, and tropical biomes as well as for non-woody vegetation.

THE RELATIVE IMPORTANCE OF THE VADOSE ZONE IN MULTIMEDIA RISK ASSESSMENT MODELING APPLIED AT A NATIONAL SCALE: AN ANALYSIS OF BENZENE USING 3MRA

EPA Science Inventory

Evaluating uncertainty and parameter sensitivity in environmental models can be a difficult task, even for low-order, single-media constructs driven by a unique set of site-specific data. The challenge of examining ever more complex, integrated, higher-order models is a formidab...

A spatial-dynamic value transfer model of economic losses from a biological invasion

Treesearch

Thomas P. Holmes; Andrew M. Liebhold; Kent F. Kovacs; Betsy Von Holle

2010-01-01

Rigorous assessments of the economic impacts of introduced species at broad spatial scales are required to provide credible information to policy makers. We propose that economic models of aggregate damages induced by biological invasions need to link microeconomic analyses of site-specific economic damages with spatial-dynamic models of value change associated with...

Linking landscape characteristics to mineral site use by band-tailed pigeons in Western Oregon: Coarse-filter conservation with fine-filter tuning

USGS Publications Warehouse

Overton, C.T.; Schmitz, R.A.; Casazza, Michael L.

2006-01-01

Mineral sites are scarce resources of high ion concentration used heavily by the Pacific Coast subpopulation of band-tailed pigeons. Over 20% of all known mineral sites used by band-tailed pigeons in western Oregon, including all hot springs, have been abandoned. Prior investigations have not analyzed stand or landscape level habitat composition in relation to band-tailed pigeon use of mineral sites. We used logistic regression models to evaluate the influence of habitat types, identified from Gap Analysis Program (GAP) products at two spatial scales, on the odds of mineral site use in Oregon (n = 69 currently used and 20 historically used). Our results indicated that the odds of current use were negatively associated with non-forested terrestrial and private land area around mineral sites. Similarly, the odds of current mineral site use were positively associated with forested and special status (GAP stewardship codes 1 and 2) land area. The most important variable associated with the odds of mineral site use was the amount of non-forested land cover at either spatial scale. Our results demonstrate the utility of meso-scale geographic information designed for regional, coarse-filter approaches to conservation in fine-filter investigation of wildlife-habitat relationships. Adjacent landcover and ownership status explain the pattern of use for known mineral sites in western Oregon. In order for conservation and management activities for band-tailed pigeons to be successful, mineral sites need to be addressed as important and vulnerable resources. Management of band-tailed pigeons should incorporate the potential for forest management activities and land ownership patterns to influence the risk of mineral site abandonment.

Bird assemblage response to restoration of fire-suppressed longleaf pine sandhills.

PubMed

Steen, David A; Conner, L M; Smith, Lora L; Provencher, Louis; Hiers, J Kevin; Pokswinski, Scott; Helms, Brian S; Guyer, Craig

2013-01-01

The ecological restoration of fire-suppressed habitats may require a multifaceted approach. Removal of hardwood trees together with reintroduction of fire has been suggested as a method of restoring fire-suppressed longleaf pine (Pinus palustris) forests; however, this strategy, although widespread, has not been evaluated on large spatial and temporal scales. We used a landscape-scale experimental design to examine how bird assemblages in fire-suppressed longleaf pine sandhills responded to fire alone or fire following mechanical removal or herbicide application to reduce hardwood levels. Individual treatments were compared to fire-suppressed controls and reference sites. After initial treatment, all sites were managed with prescribed fire, on an approximately two- to three-year interval, for over a decade. Nonmetric multidimensional scaling ordinations suggested that avian assemblages on sites that experienced any form of hardwood removal differed from assemblages on both fire-suppressed sites and reference sites 3-4 years after treatment (i.e., early posttreatment). After >10 years of prescribed burning on all sites (i.e., late posttreatment), only assemblages at sites treated with herbicide were indistinguishable from assemblages at reference sites. By the end of the study, individual species that were once indicators of reference sites no longer contributed to making reference sites unique. Occupancy modeling of these indicator species also demonstrated increasing similarity across treatments over time. Overall, although we documented long-term and variable assemblage-level change, our results indicate occupancy for birds considered longleaf pine specialists was similar at treatment and reference sites after over a decade of prescribed burning, regardless of initial method of hardwood removal. In other words, based on the response of species highly associated with the habitat, we found no justification for the added cost and effort of fire surrogates; fire alone was sufficient to restore these species.

Where to Dig for Fossils: Combining Climate-Envelope, Taphonomy and Discovery Models

PubMed Central

Block, Sebastián; Saltré, Frédérik; Rodríguez-Rey, Marta; Fordham, Damien A.; Unkel, Ingmar; Bradshaw, Corey J. A.

2016-01-01

Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites are often rare and difficult to find. The traditional fossil-hunting approach focuses on small areas and has not yet taken advantage of modelling techniques commonly used in ecology to account for an organism’s past distributions. We propose a new method to assist finding fossils at continental scales based on modelling the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field, and apply it to several genera of Australian megafauna that went extinct in the Late Quaternary. Our models predicted higher fossil potentials for independent sites than for randomly selected locations (mean Kolmogorov-Smirnov statistic = 0.66). We demonstrate the utility of accounting for the distribution history of fossil taxa when trying to find the most suitable areas to look for fossils. For some genera, the probability of finding fossils based on simple climate-envelope models was higher than the probability based on models incorporating current conditions associated with fossil preservation and discovery as predictors. However, combining the outputs from climate-envelope, preservation, and discovery models resulted in the most accurate predictions of potential fossil sites at a continental scale. We proposed potential areas to discover new fossils of Diprotodon, Zygomaturus, Protemnodon, Thylacoleo, and Genyornis, and provide guidelines on how to apply our approach to assist fossil hunting in other continents and geological settings. PMID:27027874

Where to Dig for Fossils: Combining Climate-Envelope, Taphonomy and Discovery Models.

PubMed

Block, Sebastián; Saltré, Frédérik; Rodríguez-Rey, Marta; Fordham, Damien A; Unkel, Ingmar; Bradshaw, Corey J A

2016-01-01

Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites are often rare and difficult to find. The traditional fossil-hunting approach focuses on small areas and has not yet taken advantage of modelling techniques commonly used in ecology to account for an organism's past distributions. We propose a new method to assist finding fossils at continental scales based on modelling the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field, and apply it to several genera of Australian megafauna that went extinct in the Late Quaternary. Our models predicted higher fossil potentials for independent sites than for randomly selected locations (mean Kolmogorov-Smirnov statistic = 0.66). We demonstrate the utility of accounting for the distribution history of fossil taxa when trying to find the most suitable areas to look for fossils. For some genera, the probability of finding fossils based on simple climate-envelope models was higher than the probability based on models incorporating current conditions associated with fossil preservation and discovery as predictors. However, combining the outputs from climate-envelope, preservation, and discovery models resulted in the most accurate predictions of potential fossil sites at a continental scale. We proposed potential areas to discover new fossils of Diprotodon, Zygomaturus, Protemnodon, Thylacoleo, and Genyornis, and provide guidelines on how to apply our approach to assist fossil hunting in other continents and geological settings.

Quantification of source impact to PM using three-dimensional weighted factor model analysis on multi-site data

NASA Astrophysics Data System (ADS)

Shi, Guoliang; Peng, Xing; Huangfu, Yanqi; Wang, Wei; Xu, Jiao; Tian, Yingze; Feng, Yinchang; Ivey, Cesunica E.; Russell, Armistead G.

2017-07-01

Source apportionment technologies are used to understand the impacts of important sources of particulate matter (PM) air quality, and are widely used for both scientific studies and air quality management. Generally, receptor models apportion speciated PM data from a single sampling site. With the development of large scale monitoring networks, PM speciation are observed at multiple sites in an urban area. For these situations, the models should account for three factors, or dimensions, of the PM, including the chemical species concentrations, sampling periods and sampling site information, suggesting the potential power of a three-dimensional source apportionment approach. However, the principle of three-dimensional Parallel Factor Analysis (Ordinary PARAFAC) model does not always work well in real environmental situations for multi-site receptor datasets. In this work, a new three-way receptor model, called "multi-site three way factor analysis" model is proposed to deal with the multi-site receptor datasets. Synthetic datasets were developed and introduced into the new model to test its performance. Average absolute error (AAE, between estimated and true contributions) for extracted sources were all less than 50%. Additionally, three-dimensional ambient datasets from a Chinese mega-city, Chengdu, were analyzed using this new model to assess the application. Four factors are extracted by the multi-site WFA3 model: secondary source have the highest contributions (64.73 and 56.24 μg/m3), followed by vehicular exhaust (30.13 and 33.60 μg/m3), crustal dust (26.12 and 29.99 μg/m3) and coal combustion (10.73 and 14.83 μg/m3). The model was also compared to PMF, with general agreement, though PMF suggested a lower crustal contribution.

Field scale DNAPLs transport under nonequilibrium sorption conditions.

PubMed

Ahmed, Ashraf A; Chen, Daoyi

2006-01-01

The purpose of this work is to study the desorption of dense nonaqueous phase liquids (DNAPLs), TCE in particular, from solid particles in field scale heterogeneous aquifers upon their remediation. A computer program, capable of simulating the fate and transport of NAPLs in porous media, has been developed to work under nonequilibrium sorption conditions. The model has been applied to a field scale site at Hill Air Force Base, Utah, which has been contaminated by DNAPLs. The simulated domain was 155 ft (47.25 m) long, 60 ft (18.29 m) wide, and 15.5 ft (4.72 m) thick. This thickness represents only the saturated zone of the aquifer. Changes in permeability, grain size distribution, and sorptive properties throughout the site have been incorporated into the model. Immediately after the aquifer cleanup, the DNAPL concentration in the aqueous phase was assumed to be zero, and this was considered the start-off time for the simulation. Results show that, with an increase in time, the TCE diffused out of the solid particles, forming a plume. The rate of contaminant diffusion was observed to be very fast at the start, followed by a very slow stage, with a number of years required for substantial desorption of the contaminant from the solid particles. There were local variations in contaminant concentration in the fluid phase across the site due to aquifer heterogeneity. A comparison between numerical results and water samples taken from the site after the end of the cleanup operation is also presented.

Explanatory Power of Multi-scale Physical Descriptors in Modeling Benthic Indices Across Nested Ecoregions of the Pacific Northwest

NASA Astrophysics Data System (ADS)

Holburn, E. R.; Bledsoe, B. P.; Poff, N. L.; Cuhaciyan, C. O.

2005-05-01

Using over 300 R/EMAP sites in OR and WA, we examine the relative explanatory power of watershed, valley, and reach scale descriptors in modeling variation in benthic macroinvertebrate indices. Innovative metrics describing flow regime, geomorphic processes, and hydrologic-distance weighted watershed and valley characteristics are used in multiple regression and regression tree modeling to predict EPT richness, % EPT, EPT/C, and % Plecoptera. A nested design using seven ecoregions is employed to evaluate the influence of geographic scale and environmental heterogeneity on the explanatory power of individual and combined scales. Regression tree models are constructed to explain variability while identifying threshold responses and interactions. Cross-validated models demonstrate differences in the explanatory power associated with single-scale and multi-scale models as environmental heterogeneity is varied. Models explaining the greatest variability in biological indices result from multi-scale combinations of physical descriptors. Results also indicate that substantial variation in benthic macroinvertebrate response can be explained with process-based watershed and valley scale metrics derived exclusively from common geospatial data. This study outlines a general framework for identifying key processes driving macroinvertebrate assemblages across a range of scales and establishing the geographic extent at which various levels of physical description best explain biological variability. Such information can guide process-based stratification to avoid spurious comparison of dissimilar stream types in bioassessments and ensure that key environmental gradients are adequately represented in sampling designs.

Mapping the distribution of the denitrifier community at large scales (Invited)

NASA Astrophysics Data System (ADS)

Philippot, L.; Bru, D.; Ramette, A.; Dequiedt, S.; Ranjard, L.; Jolivet, C.; Arrouays, D.

2010-12-01

Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. Here we combined molecular approaches and geostatistical modeling to explore spatial patterns of the denitrifying community at large scales. The distribution of denitrifrying community was investigated over 107 sites in Burgundy, a 31 500 km2 region of France, using a 16 X 16 km sampling grid. At each sampling site, the abundances of denitrifiers and 42 soil physico-chemical properties were measured. The relative contributions of land use, spatial distance, climatic conditions, time and soil physico-chemical properties to the denitrifier spatial distribution were analyzed by canonical variation partitioning. Our results indicate that 43% to 85% of the spatial variation in community abundances could be explained by the measured environmental parameters, with soil chemical properties (mostly pH) being the main driver. We found spatial autocorrelation up to 740 km and used geostatistical modelling to generate predictive maps of the distribution of denitrifiers at the landscape scale. Studying the distribution of the denitrifiers at large scale can help closing the artificial gap between the investigation of microbial processes and microbial community ecology, therefore facilitating our understanding of the relationships between the ecology of denitrifiers and N-fluxes by denitrification.

Construction of a 40-mile long roadside scale model of the solar system in northern Maine

NASA Astrophysics Data System (ADS)

McCartney, K.

2001-05-01

The Maine Solar System Model is currently under construction along Route 1 between Houlton and Presque Isle, in Aroostook County, northern Maine. The scale is 1:93,000,000, or 1 mile equals an astronomical unit. There is a 40 mile distance between the Sun (diameter 49.5 feet) and Pluto (diameter 1 inch). The model will include the Sun, nine planets and seven moons, with diameters and distances all to the same scale. Except for the Sun, all components will be three-dimensional and built to withstand the northern Maine climate. Construction is generally of steel with fiberglass globes positioned on steel posts at least ten feet above ground and 55 feet off the roadway. Road safety concerns require that the Jupiter and Saturn sites include parking lots. Educational information associated with the model will be provided on brochures, since textual information at the sites would require excessive stops and parking problems. Learning exercises will also be provided by travelling trunks prepared by Maine teachers to support the State of Maine Learning Results. This is a community project with the various components being built by ten area schools and with active assistance from many community members and organizations. It is being built with with very little money, with most materials and labor donated.

Onboard Science Insights and Vehicle Dynamics from Scale-Model Trials of the Titan Mare Explorer (TiME) Capsule at Laguna Negra, Chile.

PubMed

Lorenz, Ralph D; Cabrol, Nathalie A

2018-05-01

A scale model of the proposed Titan Mare Explorer capsule was deployed at the Planetary Lake Lander field site at Laguna Negra, Chile. The tests served to calibrate models of wind-driven drift of the capsule and to understand its attitude motion in the wave field, as well as to identify dynamic and acoustic signatures of shoreline approach. This information enables formulation of onboard trigger criteria for near-shore science data acquisition. Key Words: Titan-Vehicle dynamics-Science autonomy-Lake. Astrobiology 18, 607-618.

The effects of topical iodine containing antiseptics on thyroidal status of preterm versus term babies.

PubMed

Hudaoglu, Orkide G; Uçar, Sema K; Atlihan, Füsun; Dizdarer, Ceyhun; Büyükgebiz, Atilla

2009-06-01

To determine the effect of iodine containing antiseptics on thyroid function for the first 3 weeks in non-very-low-birth weight preterm and term babies, and to evaluate their thyroid function and behavioral status 7 years later. Cohort I (between the years 1997-1998) was studied in 57 preterm (30-35 weeks) and 29 term newborns, 7 years later cohort II (in the year 2005) was created from same 28 preterm and 18 term infants at Behcet Uz Children's Hospital, Izmir, Turkey. Serum thyrotropin, triiodothyronine, total and free thyroxine were measured on the first, seventh, and twenty-first days (cohort I), and at the age of 7 (cohort II). In respect of used antiseptics, the patients were divided into 2 groups. The evaluation of patients was performed according to the Turgay Diagnostic and Statistical Manual for Psychiatric Disorders, 4th edition based child and adolescent behavior disorders screening and rating scale. On the seventh day of life, iodine-exposed newborns had significantly higher mean thyrotropin levels and lower free thyroxine, total thyroxine, and triiodothyronine levels. On the twenty-first day, thyrotropin levels of iodine-exposed newborns were similar to controls. The cohort II results showed normal thyroid function in all patents with increased hyperactivity among children born prematurely, and particularly experienced exposure to iodine. Iodine excess may cause transient hypothyroxinemia in preterm babies (>30 weeks gestational age, >1.5 kg) and this may be one of the reasons for behavior problems observed later in these children.

Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes.

PubMed

De Gusseme, Bart; Hennebel, Tom; Christiaens, Eline; Saveyn, Hans; Verbeken, Kim; Fitts, Jeffrey P; Boon, Nico; Verstraete, Willy

2011-02-01

The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag(0)) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag(0) particles, preventing aggregation during encapsulation. In this study, bio-Ag(0) was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag(0) and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag(+) from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag(0)(powder) m(-2) in a submerged plate membrane reactor operated at a flux of 3.1 L m(-2) h(-1). Upon startup, the silver concentration in the effluent initially increased to 271 μg L(-1) but after filtration of 31 L m(-2), the concentration approached the drinking water limit ( = 100 μg L(-1)). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m(-2) h(-1), showing the potential of this membrane technology for water disinfection on small scale. © 2010 Elsevier Ltd. All rights reserved.

Describing Willow Flycatcher habitats: scale perspectives and gender differences

USGS Publications Warehouse

Sedgwick, James A.; Knopf, Fritz L.

1992-01-01

We compared habitat characteristics of nest sites (female-selected sites) and song perch sites (male-selected sites) with those of sites unused by Willow Flycatchers (Empidonax traillii) at three different scales of vegetation measurement: (1) microplot (central willow [Salix spp.] bush and four adjacent bushes); (2) mesoplot (0.07 ha); and, (3) macroplot (flycatcher territory size). Willow Flycatchers exhibited vegetation preferences at all three scales. Nest sites were distinguished by high willow density and low variability in willow patch size and bush height. Song perch sites were characterized by large central shrubs, low central shrub vigor, and high variability in shrub size. Unused sites were characterized by greater distances between willows and willow patches, less willow coverage, and a smaller riparian zone width than either nest or song perch sites. At all scales, nest sites were situated farther from unused sites in multivariate habitat space than were song perch sites, suggesting (1) a correspondence among scales in their ability to describe Willow Flycatcher habitat, and (2) females are more discriminating in habitat selection than males. Microhabitat differences between male-selected (song perch) and female-selected (nest) sites were evident at the two smaller scales; at the finest scale, the segregation in habitat space between male-selected and female-selected sites was greater than that between male-selected and unused sites. Differences between song perch and nest sites were not apparent at the scale of flycatcher territory size, possibly due to inclusion of (1) both nest and song perch sites, (2) defended, but unused habitat, and/or (3) habitat outside of the territory, in larger scale analyses. The differences between nest and song perch sites at the finer scales reflect their different functions (e.g., nest concealment and microclimatic requirements vs. advertising and territorial defense, respectively), and suggest that the exclusive use of either nest or song perch sites in vegetation analyses can result in misleading, or at least incomplete, descriptions of a species' habitat. Habitat interpretations for Willow Flycatchers (and perhaps for many passerines) are a function of the gender-specific behavior of the birds observed and the scale of vegetation measurement.

Merging a mechanistic enzymatic model of soil heterotrophic respiration into an ecosystem model in two AmeriFlux sites of northeastern USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sihi, Debjani; Davidson, Eric A.; Chen, Min

Heterotrophic respiration (Rh), microbial processing of soil organic matter to carbon dioxide (CO 2), is a major, yet highly uncertain, carbon (C) flux from terrestrial systems to the atmosphere. Temperature sensitivity of Rh is often represented with a simple Q 10 function in ecosystem models and earth system models (ESMs), sometimes accompanied by an empirical soil moisture modifier. More explicit representation of the effects of soil moisture, substrate supply, and their interactions with temperature has been proposed as a way to disentangle the confounding factors of apparent temperature sensitivity of Rh and improve the performance of ecosystem models and ESMs.more » The objective of this work was to insert into an ecosystem model a more mechanistic, but still parsimonious, model of environmental factors controlling Rh and evaluate the model performance in terms of soil and ecosystem respiration. The Dual Arrhenius and Michaelis-Menten (DAMM) model simulates Rh using Michaelis-Menten, Arrhenius, and diffusion functions. Soil moisture affects Rh and its apparent temperature sensitivity in DAMM by regulating the diffusion of oxygen, soluble C substrates, and extracellular enzymes to the enzymatic reaction site. Here, we merged the DAMM soil flux model with a parsimonious ecosystem flux model, FöBAAR (Forest Biomass, Assimilation, Allocation and Respiration). We used high-frequency soil flux data from automated soil chambers and landscape-scale ecosystem fluxes from eddy covariance towers at two AmeriFlux sites (Harvard Forest, MA and Howland Forest, ME) in the northeastern USA to estimate parameters, validate the merged model, and to quantify the uncertainties in a multiple constraints approach. The optimized DAMM-FöBAAR model better captured the seasonal and inter-annual dynamics of soil respiration (Soil R) compared to the FöBAAR-only model for the Harvard Forest, where higher frequency and duration of drying events significantly regulate substrate supply to heterotrophs. However, DAMM-FöBAAR showed improvement over FöBAAR-only at the boreal transition Howland Forest only in unusually dry years. The frequency of synoptic-scale dry periods is lower at Howland, resulting in only brief water limitation of Rh in some years. At both sites, the declining trend of soil R during drying events was captured by the DAMM-FöBAAR model; however, model performance was also contingent on site conditions, climate, and the temporal scale of interest. While the DAMM functions require a few more parameters than a simple Q10 function, we have demonstrated that they can be included in an ecosystem model and reduce the model-data mismatch. Moreover, the mechanistic structure of the soil moisture effects using DAMM functions should be more generalizable than the wide variety of empirical functions that are commonly used, and these DAMM functions could be readily incorporated into other ecosystem models and ESMs.« less

Interests of long-term hydrogeological observatories for characterizing and modelling heterogeneous groundwater systems at multiple temporal and spatial scales: the example of Ploemeur, a crystalline rock aquifer (Brittany).

NASA Astrophysics Data System (ADS)

Bour, Olivier; Longuervergne, Laurent; Le Borgne, Tanguy; Lavenant, Nicolas; de Dreuzy, Jean-Raynald; Schuite, Jonathan; Labasque, Thierry; Aquilina, Luc; Davy, Philippe

2017-04-01

Characterizing groundwater flows and surface interactions in heterogeneous groundwater systems such as crystalline fractured rock is often extremely complex. In particular, hydraulic properties are highly variable while groundwater chemical properties may vary both in space and time, especially due to the impact of groundwater abstraction. Here, we show the interest of hydrological observatories and long-term monitoring for characterizing hydrological processes occurring in a crystalline rock aquifer. We present results from the site of Ploemeur (French Brittany) that belongs to the network of hydrogeological sites H+ and the research infrastructure OZCAR, and where interdisciplinary and integrated research at multiple temporal and spatial scales has been developed for almost twenty years. This outstandingly heterogeneous crystalline rock aquifer is also used for groundwater supply since 1991. In particular, we show how cross-borehole flowmeter tests, pumping tests and a frequency domain analysis of groundwater levels allow quantifying the hydraulic properties of the aquifer at different scales. In addition, groundwater temperature evolution was used as an excellent tracer for characterizing groundwater flow. At the site scale, measurements of ground surface deformation through long-base tiltmeters provide robust estimates of aquifer storage and allow identifying the active structures, including those acting during recharge process. Finally, a numerical model of the watershed scale that combines hydraulic data and groundwater ages confirms the geometry of this complex aquifer and the consistency of the different datasets. In parallel, this hydrological observatory is also used for developing hydrogeophysical methods and to characterize groundwater transport and biogeochemical reactivity in the sub-surface. The Ploemeur hydrogeological observatory is a good example of the interest of focusing research activities on a site during long-term as it provides a thorough understanding of both hydrological and biogeochemical processes that can be extended to many heterogeneous aquifers.

Databases for multilevel biophysiology research available at Physiome.jp.

PubMed

Asai, Yoshiyuki; Abe, Takeshi; Li, Li; Oka, Hideki; Nomura, Taishin; Kitano, Hiroaki

2015-01-01

Physiome.jp (http://physiome.jp) is a portal site inaugurated in 2007 to support model-based research in physiome and systems biology. At Physiome.jp, several tools and databases are available to support construction of physiological, multi-hierarchical, large-scale models. There are three databases in Physiome.jp, housing mathematical models, morphological data, and time-series data. In late 2013, the site was fully renovated, and in May 2015, new functions were implemented to provide information infrastructure to support collaborative activities for developing models and performing simulations within the database framework. This article describes updates to the databases implemented since 2013, including cooperation among the three databases, interactive model browsing, user management, version management of models, management of parameter sets, and interoperability with applications.

Evolution of Precipitation Structure During the November DYNAMO MJO Event: Cloud-Resolving Model Intercomparison and Cross Validation Using Radar Observations

NASA Astrophysics Data System (ADS)

Li, Xiaowen; Janiga, Matthew A.; Wang, Shuguang; Tao, Wei-Kuo; Rowe, Angela; Xu, Weixin; Liu, Chuntao; Matsui, Toshihisa; Zhang, Chidong

2018-04-01

Evolution of precipitation structures are simulated and compared with radar observations for the November Madden-Julian Oscillation (MJO) event during the DYNAmics of the MJO (DYNAMO) field campaign. Three ground-based, ship-borne, and spaceborne precipitation radars and three cloud-resolving models (CRMs) driven by observed large-scale forcing are used to study precipitation structures at different locations over the central equatorial Indian Ocean. Convective strength is represented by 0-dBZ echo-top heights, and convective organization by contiguous 17-dBZ areas. The multi-radar and multi-model framework allows for more stringent model validations. The emphasis is on testing models' ability to simulate subtle differences observed at different radar sites when the MJO event passed through. The results show that CRMs forced by site-specific large-scale forcing can reproduce not only common features in cloud populations but also subtle variations observed by different radars. The comparisons also revealed common deficiencies in CRM simulations where they underestimate radar echo-top heights for the strongest convection within large, organized precipitation features. Cross validations with multiple radars and models also enable quantitative comparisons in CRM sensitivity studies using different large-scale forcing, microphysical schemes and parameters, resolutions, and domain sizes. In terms of radar echo-top height temporal variations, many model sensitivity tests have better correlations than radar/model comparisons, indicating robustness in model performance on this aspect. It is further shown that well-validated model simulations could be used to constrain uncertainties in observed echo-top heights when the low-resolution surveillance scanning strategy is used.

3D fully convolutional networks for subcortical segmentation in MRI: A large-scale study.

PubMed

Dolz, Jose; Desrosiers, Christian; Ben Ayed, Ismail

2018-04-15

This study investigates a 3D and fully convolutional neural network (CNN) for subcortical brain structure segmentation in MRI. 3D CNN architectures have been generally avoided due to their computational and memory requirements during inference. We address the problem via small kernels, allowing deeper architectures. We further model both local and global context by embedding intermediate-layer outputs in the final prediction, which encourages consistency between features extracted at different scales and embeds fine-grained information directly in the segmentation process. Our model is efficiently trained end-to-end on a graphics processing unit (GPU), in a single stage, exploiting the dense inference capabilities of fully CNNs. We performed comprehensive experiments over two publicly available datasets. First, we demonstrate a state-of-the-art performance on the ISBR dataset. Then, we report a large-scale multi-site evaluation over 1112 unregistered subject datasets acquired from 17 different sites (ABIDE dataset), with ages ranging from 7 to 64 years, showing that our method is robust to various acquisition protocols, demographics and clinical factors. Our method yielded segmentations that are highly consistent with a standard atlas-based approach, while running in a fraction of the time needed by atlas-based methods and avoiding registration/normalization steps. This makes it convenient for massive multi-site neuroanatomical imaging studies. To the best of our knowledge, our work is the first to study subcortical structure segmentation on such large-scale and heterogeneous data. Copyright © 2017 Elsevier Inc. All rights reserved.

Scaling up Education Reform: Addressing the Politics of Disparity

ERIC Educational Resources Information Center

Bishop, Russell; O'Sullivan, Dominic; Berryman, Mere

2010-01-01

What is school reform? What makes it sustainable? Who needs to be involved? How is scaling up achieved? This book is about the need for educational reforms that have built into them, from the outset, those elements that will see them sustained in the original sites and spread to others. Using the Te Kotahitanga Project as a model the authors…

Modelling evapotranspiration during precipitation deficits: Identifying critical processes in a land surface model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ukkola, Anna M.; Pitman, Andy J.; Decker, Mark

Surface fluxes from land surface models (LSMs) have traditionally been evaluated against monthly, seasonal or annual mean states. The limited ability of LSMs to reproduce observed evaporative fluxes under water-stressed conditions has been previously noted, but very few studies have systematically evaluated these models during rainfall deficits. We evaluated latent heat fluxes simulated by the Community Atmosphere Biosphere Land Exchange (CABLE) LSM across 20 flux tower sites at sub-annual to inter-annual timescales, in particular focusing on model performance during seasonal-scale rainfall deficits. The importance of key model processes in capturing the latent heat flux was explored by employing alternative representations of hydrology, leafmore » area index, soil properties and stomatal conductance. We found that the representation of hydrological processes was critical for capturing observed declines in latent heat during rainfall deficits. By contrast, the effects of soil properties, LAI and stomatal conductance were highly site-specific. Whilst the standard model performs reasonably well at annual scales as measured by common metrics, it grossly underestimates latent heat during rainfall deficits. A new version of CABLE, with a more physically consistent representation of hydrology, captures the variation in the latent heat flux during seasonal-scale rainfall deficits better than earlier versions, but remaining biases point to future research needs. Lastly, our results highlight the importance of evaluating LSMs under water-stressed conditions and across multiple plant functional types and climate regimes.« less

Modelling evapotranspiration during precipitation deficits: Identifying critical processes in a land surface model

DOE PAGES

Ukkola, Anna M.; Pitman, Andy J.; Decker, Mark; ...

2016-06-21

Surface fluxes from land surface models (LSMs) have traditionally been evaluated against monthly, seasonal or annual mean states. The limited ability of LSMs to reproduce observed evaporative fluxes under water-stressed conditions has been previously noted, but very few studies have systematically evaluated these models during rainfall deficits. We evaluated latent heat fluxes simulated by the Community Atmosphere Biosphere Land Exchange (CABLE) LSM across 20 flux tower sites at sub-annual to inter-annual timescales, in particular focusing on model performance during seasonal-scale rainfall deficits. The importance of key model processes in capturing the latent heat flux was explored by employing alternative representations of hydrology, leafmore » area index, soil properties and stomatal conductance. We found that the representation of hydrological processes was critical for capturing observed declines in latent heat during rainfall deficits. By contrast, the effects of soil properties, LAI and stomatal conductance were highly site-specific. Whilst the standard model performs reasonably well at annual scales as measured by common metrics, it grossly underestimates latent heat during rainfall deficits. A new version of CABLE, with a more physically consistent representation of hydrology, captures the variation in the latent heat flux during seasonal-scale rainfall deficits better than earlier versions, but remaining biases point to future research needs. Lastly, our results highlight the importance of evaluating LSMs under water-stressed conditions and across multiple plant functional types and climate regimes.« less

Spatial games with cyclic interactions: the response of empty sites

NASA Astrophysics Data System (ADS)

Brown, Bart; Pleimling, Michel

2015-03-01

Predator-prey models of the May-Leonard family employ empty sites in a spatial setting as an intermediate step in the reproduction process. This requirement makes the number and arrangement of empty sites important to the formation of space-time patterns. We study the density of empty sites in a stochastic predator-prey model in which the species compete in a cyclic way in two dimensions. In some cases systems of this type quickly form domains of neutral species after which all predation, and therefore, reproduction occur near the interface of competing domains. Using Monte Carlo simulations we investigate the relationship of this density of empty sites to the time-dependent domain length. We further explore the dynamics by introducing perturbations to the interaction rates of the system after which we measure the perturbed density, i.e. the response of empty sites, as the system relaxes. A dynamical scaling behavior is observed in the response of empty sites. This work is supported by the US National Science Foundation through Grant DMR-1205309.

Evaluating the efficacy of a landscape scale feral cat control program using camera traps and occupancy models.

PubMed

Comer, Sarah; Speldewinde, Peter; Tiller, Cameron; Clausen, Lucy; Pinder, Jeff; Cowen, Saul; Algar, Dave

2018-03-28

The impact of introduced predators is a major factor limiting survivorship and recruitment of many native Australian species. In particular, the feral cat and red fox have been implicated in range reductions and population declines of many conservation dependent species across Australia, including ground-nesting birds and small to medium-sized mammals. The impact of predation by feral cats since their introduction some 200 years ago has altered the structure of native fauna communities and led to the development of landscape-scale threat abatement via baiting programs with the feral cat bait, Eradicat. Demonstrating the effectiveness of broad-scale programs is essential for managers to fine tune delivery and timing of baiting. Efficacy of feral cat baiting at the Fortescue Marsh in the Pilbara, Western Australia was tested using camera traps and occupancy models. There was a significant decrease in probability of site occupancy in baited sites in each of the five years of this study, demonstrating both the effectiveness of aerial baiting for landscape-scale removal of feral cats, and the validity of camera trap monitoring techniques for detecting changes in feral cat occupancy during a five-year baiting program.

Natural Tracers and Multi-Scale Assessment of Caprock Sealing Behavior: A Case Study of the Kirtland Formation, San Juan Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jason Heath; Brian McPherson; Thomas Dewers

The assessment of caprocks for geologic CO{sub 2} storage is a multi-scale endeavor. Investigation of a regional caprock - the Kirtland Formation, San Juan Basin, USA - at the pore-network scale indicates high capillary sealing capacity and low permeabilities. Core and wellscale data, however, indicate a potential seal bypass system as evidenced by multiple mineralized fractures and methane gas saturations within the caprock. Our interpretation of {sup 4}He concentrations, measured at the top and bottom of the caprock, suggests low fluid fluxes through the caprock: (1) Of the total {sup 4}He produced in situ (i.e., at the locations of sampling)more » by uranium and thorium decay since deposition of the Kirtland Formation, a large portion still resides in the pore fluids. (2) Simple advection-only and advection-diffusion models, using the measured {sup 4}He concentrations, indicate low permeability ({approx}10-20 m{sup 2} or lower) for the thickness of the Kirtland Formation. These findings, however, do not guarantee the lack of a large-scale bypass system. The measured data, located near the boundary conditions of the models (i.e., the overlying and underlying aquifers), limit our testing of conceptual models and the sensitivity of model parameterization. Thus, we suggest approaches for future studies to better assess the presence or lack of a seal bypass system at this particular site and for other sites in general.« less

Local and landscape scale factors influencing edge effects on woodland salamanders.

PubMed

Moseley, Kurtis R; Ford, W Mark; Edwards, John W

2009-04-01

We examined local and landscape-scale variable influence on the depth and magnitude of edge effects on woodland salamanders in mature mixed mesophytic and northern hardwood forest adjacent to natural gas well sites maintained as wildlife openings. We surveyed woodland salamander occurrence from June-August 2006 at 33 gas well sites in the Monongahela National Forest, West Virginia. We used an information-theoretic approach to test nine a priori models explaining landscape-scale effects on woodland salamander capture proportion within 20 m of field edge. Salamander capture proportion was greater within 0-60 m than 61-100 m of field edges. Similarly, available coarse woody debris proportion was greater within 0-60 m than 61-100 m of field edge. Our ASPECT model, that incorporated the single variable aspect, received the strongest support for explaining landscape-scale effects on salamander capture proportion within 20 m of opening edge. The ASPECT model indicated that fewer salamanders occurred within 20 m of opening edges on drier, hotter southwestern aspects than in moister, cooler northeastern aspects. Our results suggest that forest habitat adjacent to maintained edges and with sufficient cover still can provide suitable habitat for woodland salamander species in central Appalachian mixed mesophytic and northern hardwood forests. Additionally, our modeling results support the contention that edge effects are more severe on southwesterly aspects. These results underscore the importance of distinguishing among different edge types as well as placing survey locations within a landscape context when investigating edge impacts on woodland salamanders.

A Model-based Approach to Scaling GPP and NPP in Support of MODIS Land Product Validation

NASA Astrophysics Data System (ADS)

Turner, D. P.; Cohen, W. B.; Gower, S. T.; Ritts, W. D.

2003-12-01

Global products from the Earth-orbiting MODIS sensor include land cover, leaf area index (LAI), FPAR, 8-day gross primary production (GPP), and annual net primary production (NPP) at the 1 km spatial resolution. The BigFoot Project was designed specifically to validate MODIS land products, and has initiated ground measurements at 9 sites representing a wide array of vegetation types. An ecosystem process model (Biome-BGC) is used to generate estimates of GPP and NPP for each 5 km x 5 km BigFoot site. Model inputs include land cover and LAI (from Landsat ETM+), daily meteorological data (from a centrally located eddy covariance flux tower), and soil characteristics. Model derived outputs are validated against field-measured NPP and flux tower-derived GPP. The resulting GPP and NPP estimates are then aggregated to the 1 km resolution for direct spatial comparison with corresponding MODIS products. At the high latitude sites (tundra and boreal forest), the MODIS GPP phenology closely tracks the BigFoot GPP, but there is a high bias in the MODIS GPP. In the temperate zone sites, problems with the timing and magnitude of the MODIS FPAR introduce differences in MODIS GPP compared to the validation data at some sites. However, the MODIS LAI/FPAR data are currently being reprocessed (=Collection 4) and new comparisons will be made for 2002. The BigFoot scaling approach permits precise overlap in spatial and temporal resolution between the MODIS products and BigFoot products, and thus permits the evaluation of specific components of the MODIS NPP algorithm. These components include meteorological inputs from the NASA Data Assimilation Office, LAI and FPAR from other MODIS algorithms, and biome-specific parameters for base respiration rate and light use efficiency.

Atmospheric studies in complex terrain: a planning guide for future studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orgill, M.M.

The objective of this study is to assist the US Department of Energy in Conducting its atmospheric studies in complex terrain (ASCOT0 by defining various complex terrain research systems and relating these options to specific landforms sites. This includes: (1) reviewing past meteorological and diffusion research on complex terrain; (2) relating specific terrain-induced airflow phenomena to specific landforms and time and space scales; (3) evaluating the technical difficulty of modeling and measuring terrain-induced airflow phenomena; and (4) avolving severdal research options and proposing candidate sites for continuing and expanding field and modeling work. To evolve research options using variable candidatemore » sites, four areas were considered: site selection, terrain uniqueness and quantification, definition of research problems and research plans. 36 references, 111 figures, 20 tables.« less

Surface-subsurface flow modeling: an example of large-scale research at the new NEON user facility

NASA Astrophysics Data System (ADS)

Powell, H.; McKnight, D. M.

2009-12-01

Climate change is predicted to alter surface-subsurface interactions in freshwater ecosystems. These interactions are hypothesized to control nutrient release at diel and seasonal time scales, which may then exert control over epilithic algal growth rates. The mechanisms underlying shifts in complex physical-chemical-biological patterns can be elucidated by long-term observations at sites that span hydrologic and climate gradients across the continent. Development of the National Ecological Observatory Network (NEON) will provide researchers the opportunity to investigate continental-scale patterns by combining investigator-driven measurements with Observatory data. NEON is a national-scale research platform for analyzing and understanding the impacts of climate change, land-use change, and invasive species on ecology. NEON features sensor networks and experiments, linked by advanced cyberinfrastructure to record and archive ecological data for at least 30 years. NEON partitions the United States into 20 ecoclimatic domains. Each domain hosts one fully instrumented Core Aquatic site in a wildland area and one Relocatable site, which aims to capture ecologically significant gradients (e.g. landuse, nitrogen deposition, urbanization). In the current definition of NEON there are 36 Aquatic sites: 30 streams/rivers and 6 ponds/lakes. Each site includes automated, in-situ sensors for groundwater elevation and temperature; stream flow (discharge and stage); pond water elevation; atmospheric chemistry (Tair, barometric pressure, PAR, radiation); and surface water chemistry (DO, Twater, conductivity, pH, turbidity, cDOM, nutrients). Groundwater and surface water sites shall be regularly sampled for selected chemical and isotopic parameters. The hydrologic and geochemical monitoring design provides basic information on water and chemical fluxes in streams and ponds and between groundwater and surface water, which is intended to support investigator-driven modeling studies. Theoretical constructs, such as the River Continuum Concept, that aim to elucidate general mechanistic underpinnings of freshwater ecosystem function via testable hypotheses about relative rates of photosynthesis and respiration, for example, may be readily examined using data collected at hourly time scales at the NEON facility once constructed. By taking advantage of NEON data and adding PI-driven research to the Observatory, we can further our understanding of the relative roles of water flow, nutrients, temperature, and light on freshwater ecosystem function and structure.

Use of a handheld low-cost sensor to explore the effect of urban design features on local-scale spatial and temporal air quality variability.

PubMed

Miskell, Georgia; Salmond, Jennifer A; Williams, David E

2018-04-01

Portable low-cost instruments have been validated and used to measure ambient nitrogen dioxide (NO 2 ) at multiple sites over a small urban area with 20min time resolution. We use these results combined with land use regression (LUR) and rank correlation methods to explore the effects of traffic, urban design features, and local meteorology and atmosphere chemistry on small-scale spatio-temporal variations. We measured NO 2 at 45 sites around the downtown area of Vancouver, BC, in spring 2016, and constructed four different models: i) a model based on averaging concentrations observed at each site over the whole measurement period, and separate temporal models for ii) morning, iii) midday, and iv) afternoon. Redesign of the temporal models using the average model predictors as constants gave three 'hybrid' models that used both spatial and temporal variables. These accounted for approximately 50% of the total variation with mean absolute error±5ppb. Ranking sites by concentration and by change in concentration across the day showed a shift of high NO 2 concentrations across the central city from morning to afternoon. Locations could be identified in which NO 2 concentration was determined by the geography of the site, and others as ones in which the concentration changed markedly from morning to afternoon indicating the importance of temporal controls. Rank correlation results complemented LUR in identifying significant urban design variables that impacted NO 2 concentration. High variability across a relatively small space was partially described by predictor variables related to traffic (bus stop density, speed limits, traffic counts, distance to traffic lights), atmospheric chemistry (ozone, dew point), and environment (land use, trees). A high-density network recording continuously would be needed fully to capture local variations. Copyright © 2017 Elsevier B.V. All rights reserved.

THM large spatial-temporal model to simulate the past 2 Ma hydrogeological evolution of Paris Basin including natural tracer transport as part of site characterization for radwaste repository project Cigéo - France

NASA Astrophysics Data System (ADS)

Benabderrahmane, A., Sr.

2017-12-01

Hydrogeological site characterization for deep geological high level and intermediate level long lived radioactive waste repository cover a large time scale needed for safety analysis and calculation. Hydrogeological performance of a site relies also on the effects of geodynamic evolution as tectonic uplift, erosion/sedimentation and climate including glaciation on the groundwater flow and solute and heat transfer. Thermo-Hydro-Mechanical model of multilayered aquifer system of Paris Basin is developed to reproduce the present time flow and the natural tracer (Helium) concentration profiles based on the last 2 Ma of geodynamic evolution. Present time geological conceptual model consist of 27 layers at Paris Basin (Triassic-Tertiary) with refinement at project site scale (29 layers from Triassic to Portlandian). Target layers are the clay host formation of Callovo-Oxfrodian age (160 Ma) and the surrounding aquifer layers of Oxfordian and Dogger. Modelled processes are: groundwater flow, heat and solutes (natural tracers) transport, freezing and thawing of groundwater (expansion and retreat of permafrost), deformation of the multilayered aquifer system induced by differential tectonic uplift and the hydro-mechanical stress effect as caused by erosion of the outcropping layers. Numerical simulation considers a period from 2 Ma BP and up to the present. Transient boundary conditions are governed by geodynamic processes: (i) modification of the geometry of the basin and (ii) temperatures along the topography will change according to a series of 15 identical climate cycles with multiple permafrost (glaciation) periods. Numerical model contains 71 layers and 18 million cells. The solution procedure solves three coupled systems of equations, head, temperature and concentrations, by the use of a finite difference method, and by applying extensive parallel processing. The major modelling results related to the processes of importance for site characterization as hydraulic head distribution, flow velocity, heat and natural tracer transport impacted by geodynamic past evolution are discussed.

Is substrate composition a suitable predictor for deep-water coral occurrence on fine scales?

NASA Astrophysics Data System (ADS)

Bennecke, Swaantje; Metaxas, Anna

2017-06-01

Species distribution modelling can be applied to identify potentially suitable habitat for species with largely unknown distributions, such as many deep-water corals. Important variables influencing species occurrence in the deep sea, e.g. substrate composition, are often not included in these modelling approaches because high-resolution data are unavailable. We investigated the relationship between substrate composition and the occurrence of the two deep-water octocoral species Primnoa resedaeformis and Paragorgia arborea, which require hard substrate for attachment. On a scale of 10s of metres, we analysed images of the seafloor taken at two locations inside the Northeast Channel Coral Conservation Area in the Northwest Atlantic. We interpolated substrate composition over the sampling areas and determined the contribution of substrate classes, depth and slope to describe habitat suitability using maximum entropy modelling (Maxent). Substrate composition was similar at both sites - dominated by pebbles in a matrix of sand (>80%) with low percentages of suitable substrate for coral occurrence. Coral abundance was low at site 1 (0.9 colonies of P. resedaeformis per 100 m2) and high at site 2 (63 colonies of P. resedaeformis per 100 m2) indicating that substrate alone is not sufficient to explain varying patterns in coral occurrence. Spatial interpolations of substrate classes revealed the difficulty to accurately resolve sparsely distributed boulders (3-5% of substrate). Boulders were by far the most important variable in the habitat suitability model (HSM) for P. resedaeformis at site 1, indicating the fundamental influence of a substrate class that is the least abundant. At site 2, HSMs identified cobbles and sand/pebble as the most important variables for habitat suitability. However, substrate classes were correlated making it difficult to determine the influence of individual variables. To provide accurate information on habitat suitability for the two coral species, substrate composition needs to be quantified so that small fractions (<20% contribution of certain substrate class) of suitable substrate are resolved. While the collection and analysis of high-resolution data is costly and spatially limited, the required resolution is unlikely to be achieved in coarse-scale interpolations of substrate data.

Catchment-scale modeling of nitrogen dynamics in a temperate forested watershed, Oregon. An interdisciplinary communication strategy.

Treesearch

Kellie Vache; Lutz Breuer; Julia Jones; Phil Sollins

2015-01-01

We present a systems modeling approach to the development of a place-based ecohydrological model. The conceptual model is calibrated to a variety of existing observations, taken in watershed 10 (WS10) at the HJ Andrews Experimental Forest (HJA) in Oregon, USA, a long term ecological research (LTER) site with a long history of catchment-...

Efficiency of small scale carbon mitigation by patch iron fertilization

NASA Astrophysics Data System (ADS)

Sarmiento, J. L.; Slater, R. D.; Dunne, J.; Gnanadesikan, A.; Hiscock, M. R.

2009-11-01

While nutrient depletion scenarios have long shown that the high-latitude High Nutrient Low Chlorophyll (HNLC) regions are the most effective for sequestering atmospheric carbon dioxide, recent simulations with prognostic biogeochemical models have suggested that only a fraction of the potential drawdown can be realized. We use a global ocean biogeochemical general circulation model developed at GFDL and Princeton to examine this and related issues. We fertilize two patches in the North and Equatorial Pacific, and two additional patches in the Southern Ocean HNLC region north of the biogeochemical divide and in the Ross Sea south of the biogeochemical divide. We obtain by far the greatest response to iron fertilization at the Ross Sea site. Here the CO2 remains sequestered on century time-scales and the efficiency of fertilization remains almost constant no matter how frequently iron is applied as long as it is confined to the growing season. The second most efficient site is in the Southern Ocean. Here the biological response to iron fertilization is comparable to the Ross Sea, but the enhanced biological uptake of CO2 is more spread out in the vertical and thus less effective at leading to removal of CO2 from the atmosphere. The North Pacific site has lower initial nutrients and thus a lower efficiency. Fertilization of the Equatorial Pacific leads to an expansion of the suboxic zone and a striking increase in denitrification that causes a sharp reduction in overall surface biological export production and CO2 uptake. The impacts on the oxygen distribution and surface biological export are less prominent at other sites, but nevertheless still a source of concern. The century time scale retention of iron in these models greatly increases the long-term biological response to iron addition as compared with models in which the added iron is rapidly scavenged from the ocean.

Evaluation of simulations to understand effects of groundwater development and artificial recharge on the surface water and riparian vegetation Sierra Vista subwatershed, Upper San Pedro Basin, Arizona

USGS Publications Warehouse

Leake, Stanley A.; Gungle, Bruce

2012-01-01

In 2007, the U.S. Geological Survey documented a five-layer groundwater flow model of the Sierra Vista and Sonoran subwatersheds of the Upper San Pedro Basin. The model has been applied by a private consultant to evaluate the effects of projected groundwater pumping through 2105 and effects of artificial recharge at three near-stream sites for 2012-2111. The main concern regarding simulations of long-term groundwater pumping is the effect of artificial model boundaries on modeled response, particularly for pumping near Cananea, Sonora, Mexico, which is adjacent to an artificial no-flow boundary. Concerns regarding the simulations of the effects of artificial recharge near streams include the resolution of the model and the representation of the model properties at the site scale; a possible limited ability of the model to correctly apportion recharge response between increased streamflow and increased evapotranspiration; a limited ability of the model to simulate detailed geometries of artificial recharge areas and evapotranspiration areas; and stream locations with the 820-foot grid spacing of the basin-scale model. In spite of these concerns, use of the U.S. Geological Survey five-layer groundwater flow model by the consultant are reasonable and valid.

A Multiple-Item Scale for Assessing E-Government Service Quality

NASA Astrophysics Data System (ADS)

Papadomichelaki, Xenia; Mentzas, Gregoris

A critical element in the evolution of e-governmental services is the development of sites that better serve the citizens’ needs. To deliver superior service quality, we must first understand how citizens perceive and evaluate online citizen service. This involves defining what e-government service quality is, identifying its underlying dimensions, and determining how it can be conceptualized and measured. In this article we conceptualise an e-government service quality model (e-GovQual) and then we develop, refine, validate, confirm and test a multiple-item scale for measuring e-government service quality for public administration sites where citizens seek either information or services.

Mesoscale carbon sequestration site screening and CCS infrastructure analysis.

PubMed

Keating, Gordon N; Middleton, Richard S; Stauffer, Philip H; Viswanathan, Hari S; Letellier, Bruce C; Pasqualini, Donatella; Pawar, Rajesh J; Wolfsberg, Andrew V

2011-01-01

We explore carbon capture and sequestration (CCS) at the meso-scale, a level of study between regional carbon accounting and highly detailed reservoir models for individual sites. We develop an approach to CO(2) sequestration site screening for industries or energy development policies that involves identification of appropriate sequestration basin, analysis of geologic formations, definition of surface sites, design of infrastructure, and analysis of CO(2) transport and storage costs. Our case study involves carbon management for potential oil shale development in the Piceance-Uinta Basin, CO and UT. This study uses new capabilities of the CO(2)-PENS model for site screening, including reservoir capacity, injectivity, and cost calculations for simple reservoirs at multiple sites. We couple this with a model of optimized source-sink-network infrastructure (SimCCS) to design pipeline networks and minimize CCS cost for a given industry or region. The CLEAR(uff) dynamical assessment model calculates the CO(2) source term for various oil production levels. Nine sites in a 13,300 km(2) area have the capacity to store 6.5 GtCO(2), corresponding to shale-oil production of 1.3 Mbbl/day for 50 years (about 1/4 of U.S. crude oil production). Our results highlight the complex, nonlinear relationship between the spatial deployment of CCS infrastructure and the oil-shale production rate.

A multi-scale comparison of modeled and observed seasonal methane emissions in northern wetlands

DOE PAGES

Xu, Xiyan; Riley, William J.; Koven, Charles D.; ...

2016-09-13

Wetlands are the largest global natural methane (CH 4) source, and emissions between 50 and 70° N latitude contribute 10-30 % to this source. Predictive capability of land models for northern wetland CH 4 emissions is still low due to limited site measurements, strong spatial and temporal variability in emissions, and complex hydrological and biogeochemical dynamics. To explore this issue, we compare wetland CH 4 emission predictions from the Community Land Model 4.5 (CLM4.5-BGC) with site- to regional-scale observations. A comparison of the CH 4 fluxes with eddy flux data highlighted needed changes to the model's estimate of aerenchyma area,more » which we implemented and tested. The model modification substantially reduced biases in CH 4 emissions when compared with CarbonTracker CH 4 predictions. CLM4.5 CH 4 emission predictions agree well with growing season (May–September) CarbonTracker Alaskan regional-level CH 4 predictions and site-level observations. However, CLM4.5 underestimated CH 4 emissions in the cold season (October–April). The monthly atmospheric CH 4 mole fraction enhancements due to wetland emissions are also assessed using the Weather Research and Forecasting-Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) model coupled with daily emissions from CLM4.5 and compared with aircraft CH 4 mole fraction measurements from the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) campaign. Both the tower and aircraft analyses confirm the underestimate of cold-season CH 4 emissions by CLM4.5. The greatest uncertainties in predicting the seasonal CH 4 cycle are from the wetland extent, cold-season CH 4 production and CH 4 transport processes. We recommend more cold-season experimental studies in high-latitude systems, which could improve the understanding and parameterization of ecosystem structure and function during this period. Predicted CH 4 emissions remain uncertain, but we show here that benchmarking against observations across spatial scales can inform model structural and parameter improvements.« less

A multi-scale comparison of modeled and observed seasonal methane emissions in northern wetlands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Xiyan; Riley, William J.; Koven, Charles D.

Wetlands are the largest global natural methane (CH 4) source, and emissions between 50 and 70° N latitude contribute 10-30 % to this source. Predictive capability of land models for northern wetland CH 4 emissions is still low due to limited site measurements, strong spatial and temporal variability in emissions, and complex hydrological and biogeochemical dynamics. To explore this issue, we compare wetland CH 4 emission predictions from the Community Land Model 4.5 (CLM4.5-BGC) with site- to regional-scale observations. A comparison of the CH 4 fluxes with eddy flux data highlighted needed changes to the model's estimate of aerenchyma area,more » which we implemented and tested. The model modification substantially reduced biases in CH 4 emissions when compared with CarbonTracker CH 4 predictions. CLM4.5 CH 4 emission predictions agree well with growing season (May–September) CarbonTracker Alaskan regional-level CH 4 predictions and site-level observations. However, CLM4.5 underestimated CH 4 emissions in the cold season (October–April). The monthly atmospheric CH 4 mole fraction enhancements due to wetland emissions are also assessed using the Weather Research and Forecasting-Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) model coupled with daily emissions from CLM4.5 and compared with aircraft CH 4 mole fraction measurements from the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) campaign. Both the tower and aircraft analyses confirm the underestimate of cold-season CH 4 emissions by CLM4.5. The greatest uncertainties in predicting the seasonal CH 4 cycle are from the wetland extent, cold-season CH 4 production and CH 4 transport processes. We recommend more cold-season experimental studies in high-latitude systems, which could improve the understanding and parameterization of ecosystem structure and function during this period. Predicted CH 4 emissions remain uncertain, but we show here that benchmarking against observations across spatial scales can inform model structural and parameter improvements.« less

A method for deterministic statistical downscaling of daily precipitation at a monsoonal site in Eastern China

NASA Astrophysics Data System (ADS)

Liu, Yonghe; Feng, Jinming; Liu, Xiu; Zhao, Yadi

2017-12-01

Statistical downscaling (SD) is a method that acquires the local information required for hydrological impact assessment from large-scale atmospheric variables. Very few statistical and deterministic downscaling models for daily precipitation have been conducted for local sites influenced by the East Asian monsoon. In this study, SD models were constructed by selecting the best predictors and using generalized linear models (GLMs) for Feixian, a site in the Yishu River Basin and Shandong Province. By calculating and mapping Spearman rank correlation coefficients between the gridded standardized values of five large-scale variables and daily observed precipitation, different cyclonic circulation patterns were found for monsoonal precipitation in summer (June-September) and winter (November-December and January-March); the values of the gridded boxes with the highest absolute correlations for observed precipitation were selected as predictors. Data for predictors and predictands covered the period 1979-2015, and different calibration and validation periods were divided when fitting and validating the models. Meanwhile, the bootstrap method was also used to fit the GLM. All the above thorough validations indicated that the models were robust and not sensitive to different samples or different periods. Pearson's correlations between downscaled and observed precipitation (logarithmically transformed) on a daily scale reached 0.54-0.57 in summer and 0.56-0.61 in winter, and the Nash-Sutcliffe efficiency between downscaled and observed precipitation reached 0.1 in summer and 0.41 in winter. The downscaled precipitation partially reflected exact variations in winter and main trends in summer for total interannual precipitation. For the number of wet days, both winter and summer models were able to reflect interannual variations. Other comparisons were also made in this study. These results demonstrated that when downscaling, it is appropriate to combine a correlation-based predictor selection across a spatial domain with GLM modeling.

Three-dimensional displays for natural hazards analysis, using classified Landsat Thematic Mapper digital data and large-scale digital elevation models

NASA Technical Reports Server (NTRS)

Butler, David R.; Walsh, Stephen J.; Brown, Daniel G.

1991-01-01

Methods are described for using Landsat Thematic Mapper digital data and digital elevation models for the display of natural hazard sites in a mountainous region of northwestern Montana, USA. Hazard zones can be easily identified on the three-dimensional images. Proximity of facilities such as highways and building locations to hazard sites can also be easily displayed. A temporal sequence of Landsat TM (or similar) satellite data sets could also be used to display landscape changes associated with dynamic natural hazard processes.

Scaling of Sediment Dynamics in a Reach-Scale Laboratory Model of a Sand-Bed Stream with Riparian Vegetation

NASA Astrophysics Data System (ADS)

Gorrick, S.; Rodriguez, J. F.

2011-12-01

A movable bed physical model was designed in a laboratory flume to simulate both bed and suspended load transport in a mildly sinuous sand-bed stream. Model simulations investigated the impact of different vegetation arrangements along the outer bank to evaluate rehabilitation options. Preserving similitude in the 1:16 laboratory model was very important. In this presentation the scaling approach, as well as the successes and challenges of the strategy are outlined. Firstly a near-bankfull flow event was chosen for laboratory simulation. In nature, bankfull events at the field site deposit new in-channel features but cause only small amounts of bank erosion. Thus the fixed banks in the model were not a drastic simplification. Next, and as in other studies, the flow velocity and turbulence measurements were collected in separate fixed bed experiments. The scaling of flow in these experiments was simply maintained by matching the Froude number and roughness levels. The subsequent movable bed experiments were then conducted under similar hydrodynamic conditions. In nature, the sand-bed stream is fairly typical; in high flows most sediment transport occurs in suspension and migrating dunes cover the bed. To achieve similar dynamics in the model equivalent values of the dimensionless bed shear stress and the particle Reynolds number were important. Close values of the two dimensionless numbers were achieved with lightweight sediments (R=0.3) including coal and apricot pips with a particle size distribution similar to that of the field site. Overall the moveable bed experiments were able to replicate the dominant sediment dynamics present in the stream during a bankfull flow and yielded relevant information for the analysis of the effects of riparian vegetation. There was a potential conflict in the strategy, in that grain roughness was exaggerated with respect to nature. The advantage of this strategy is that although grain roughness is exaggerated, the similarity of bedforms and resulting drag can return similar levels of roughness to those in the field site.

A methodology for ecosystem-scale modeling of selenium

USGS Publications Warehouse

Presser, T.S.; Luoma, S.N.

2010-01-01

The main route of exposure for selenium (Se) is dietary, yet regulations lack biologically based protocols for evaluations of risk. We propose here an ecosystem-scale model that conceptualizes and quantifies the variables that determinehow Se is processed from water through diet to predators. This approach uses biogeochemical and physiological factors from laboratory and field studies and considers loading, speciation, transformation to particulate material, bioavailability, bioaccumulation in invertebrates, and trophic transfer to predators. Validation of the model is through data sets from 29 historic and recent field case studies of Se-exposed sites. The model links Se concentrations across media (water, particulate, tissue of different food web species). It can be used to forecast toxicity under different management or regulatory proposals or as a methodology for translating a fish-tissue (or other predator tissue) Se concentration guideline to a dissolved Se concentration. The model illustrates some critical aspects of implementing a tissue criterion: 1) the choice of fish species determines the food web through which Se should be modeled, 2) the choice of food web is critical because the particulate material to prey kinetics of bioaccumulation differs widely among invertebrates, 3) the characterization of the type and phase of particulate material is important to quantifying Se exposure to prey through the base of the food web, and 4) the metric describing partitioning between particulate material and dissolved Se concentrations allows determination of a site-specific dissolved Se concentration that would be responsible for that fish body burden in the specific environment. The linked approach illustrates that environmentally safe dissolved Se concentrations will differ among ecosystems depending on the ecological pathways and biogeochemical conditions in that system. Uncertainties and model sensitivities can be directly illustrated by varying exposure scenarios based on site-specific knowledge. The model can also be used to facilitate site-specific regulation and to present generic comparisons to illustrate limitations imposed by ecosystem setting and inhabitants. Used optimally, the model provides a tool for framing a site-specific ecological problem or occurrence of Se exposure, quantify exposure within that ecosystem, and narrow uncertainties abouthowto protect it by understanding the specifics of the underlying system ecology, biogeochemistry, and hydrology.?? 2010 SETAC.

A methodology for ecosystem-scale modeling of selenium.

PubMed

Presser, Theresa S; Luoma, Samuel N

2010-10-01

The main route of exposure for selenium (Se) is dietary, yet regulations lack biologically based protocols for evaluations of risk. We propose here an ecosystem-scale model that conceptualizes and quantifies the variables that determine how Se is processed from water through diet to predators. This approach uses biogeochemical and physiological factors from laboratory and field studies and considers loading, speciation, transformation to particulate material, bioavailability, bioaccumulation in invertebrates, and trophic transfer to predators. Validation of the model is through data sets from 29 historic and recent field case studies of Se-exposed sites. The model links Se concentrations across media (water, particulate, tissue of different food web species). It can be used to forecast toxicity under different management or regulatory proposals or as a methodology for translating a fish-tissue (or other predator tissue) Se concentration guideline to a dissolved Se concentration. The model illustrates some critical aspects of implementing a tissue criterion: 1) the choice of fish species determines the food web through which Se should be modeled, 2) the choice of food web is critical because the particulate material to prey kinetics of bioaccumulation differs widely among invertebrates, 3) the characterization of the type and phase of particulate material is important to quantifying Se exposure to prey through the base of the food web, and 4) the metric describing partitioning between particulate material and dissolved Se concentrations allows determination of a site-specific dissolved Se concentration that would be responsible for that fish body burden in the specific environment. The linked approach illustrates that environmentally safe dissolved Se concentrations will differ among ecosystems depending on the ecological pathways and biogeochemical conditions in that system. Uncertainties and model sensitivities can be directly illustrated by varying exposure scenarios based on site-specific knowledge. The model can also be used to facilitate site-specific regulation and to present generic comparisons to illustrate limitations imposed by ecosystem setting and inhabitants. Used optimally, the model provides a tool for framing a site-specific ecological problem or occurrence of Se exposure, quantify exposure within that ecosystem, and narrow uncertainties about how to protect it by understanding the specifics of the underlying system ecology, biogeochemistry, and hydrology. © 2010 SETAC.

Informing Carbon Dynamics in the Community Land Model with Observations from Across Timescales

NASA Astrophysics Data System (ADS)

Fox, A. M.; Hoar, T. J.

2014-12-01

Correct simulation of carbon dynamics in Earth System Models is required to accurately predict both short and long-term land carbon-cycle climate and concentration feedbacks. As new model structures and parameterizations of increasing complexity are introduced there is an ever present need for data to inform these developments, either indirectly through benchmarking activities, or directly through model-data fusion techniques. Here we briefly describe a very rich source of data that will come from the National Ecological Observatory Network (NEON), a continental-scale facility that will collect freely available biogeochemical and biophysical data from 60 sites representative of a full range of ecosystems across the USA over 30 years. Relevant data at each site include a full suite of micrometeorology measurements, profiles of CO2 and H2O vapor isotopes, soil temperature, moisture and CO2 flux, fine root images, and plot-based NPP, leaf area and litterfall estimates. This is accompanied by Lidar and hyperspectral derived biomass, leaf area and canopy chemistry at < 1m resolution of 100s km2. Critically, these observations are well calibrated and highly standardized across sites allowing comparisons, whilst plot and site selection has been designed to optimize representativeness and spatial scaling opportunities. To illustrate the potential utility of these data in constraining models, we show the range of Community Land Model (CLM) output at NEON site locations, and in model-space look at a number of different functional responses that characterize the model in space and time and could be tested with data. These observations can be used most directly through a data assimilation (DA) system and we demonstrate how we have developed support for CLM within the Data Assimilation Research Testbed (DART) that uses ensemble techniques for state estimation. Using an observing system experiment, we investigate how infrequent observations of carbon stocks constrain model dynamics and how these observations types can be used with more frequently available flux and leaf area index observations. We demonstrate the use of the latter with real Ameriflux and MODIS data.

Geophysical constraints on contaminant transport modeling in a heterogeneous fluvial aquifer.

PubMed

Bowling, Jerry C; Zheng, Chunmiao; Rodriguez, Antonio B; Harry, Dennis L

2006-05-05

Approximately 3000 measurements of hydraulic conductivity in over 50 flowmeter boreholes were available at the Macro-Dispersion Experiment (MADE) site in Columbus, Mississippi, USA to quantify the heterogeneity in hydraulic conductivity at the site scale. This high-density measurement approach is perhaps infeasible for time and expense in typical groundwater remediation sites. A natural-gradient tracer experiment from the MADE site was simulated by a groundwater flow and solute transport model incorporating direct-current (DC) resistivity data collected over the observed plume location. Hydraulic conductivity from one borehole collected during the original site characterization was used to calibrate the electrical resistivity data to hydraulic conductivity using a previously derived log-log relationship. Application of this relationship, using site-specific empirical constants determined from the data, transforms the 3D electrical resistivity data into a 3D description of hydraulic conductivity that can be used in groundwater models. The validity of this approach was tested by using the geophysically derived hydraulic conductivity representation in numerical simulations of the natural-gradient tracer experiment. The agreement between the simulated and observed tracer plumes was quantified to gauge the effectiveness of geophysically derived and flowmeter based representations of the hydraulic conductivity field. This study demonstrates that a highly heterogeneous aquifer can be modeled with minimal hydrological data supplemented with geophysical data at least as well as previous models of the site using purely hydrologic data.

Fine Scale Modeling and Forecasts of Upper Atmospheric Turbulence for Operational Use

DTIC Science & Technology

2014-11-30

Weather Center Digital Data Service (ADDS) fhttp://www.aviationweather.gov/adds, http://weather.aero/1 Graphical Turbulence Guidance product, GTG -2.5...analysis GTG - Graphical Turbulence Guidance HRMM - High Resolution Mesoscale/Microscale ICD - Interface Control Document IDE - Integrated Development...site (with GTG 2.5 data) http://www.aviationweather.gov/turbuience • ADDS Experimental site http://weather.aero/ • NCEP FNL data - http

Integrated experimental and modeling assessment of potential effects of gas leakages on groundwater composition

NASA Astrophysics Data System (ADS)

Berta, Marton; Dethlefsen, Frank; Ebert, Markus; Schäfer, Dirk

2017-04-01

Storing renewably produced energy is one of the major challenges for the energy systems of the upcoming decades. Power-to-gas technologies coupled to geological storage of compressed air, methane, and hydrogen offer a comparatively safe and cost-efficient way for large-scale energy storage. However, the stored gases can potentially escape from their geological reservoir and may thus affect protected natural goods such as groundwater. The geochemical reactions responsible for these composition changes are usually investigated separately in experiments and numerical models. Here we present the outcomes of an integrated experimental and modeling approach through the example of a compressed air leakage scenario. A main consequence of the presence of oxygen to be assessed in an aquifer is pyrite oxidation, well known from acid mine drainage sites. However, in contrast to acid mine drainage sites exhibiting unsaturated sediments and fed by meteoric low-carbonate water, aquifers such as in Northern Germany contain a considerable amount of solid and dissolved inorganic carbon species potentially buffering pH changes. High pressure flow-through column experiments representing an intrusion of compressed air into an aquifer were carried out to quantify pyrite oxidation kinetics and to incorporate the observations into a descriptive reaction model. Surface passivation was found to decrease the reactivity of pyrite by more than 90% after a few months of experimental run time. We propose that the carbonate buffer system enables the precipitation of a passivating mineral layer on the pyrite surface reducing the overall reaction rate significantly. Consequently, an established rate law from the literature was extended by a reactive surface passivation term[1]. This improved reaction rate equation was incorporated into a 3D numerical model using OpenGeoSys with parameters representing similarly typical aquifer conditions the experiments had characterized. These boundaries include pyrite content, oxygen dissolution kinetics, groundwater composition including the carbonate buffer, and diffusive and advective transport parameters. The results of site-scale multiphase reactive transport modeling revealed the expected spatial distribution of redox-sensitive species such as oxygen, pyrite, and sulfate in an aquifer following a leakage. The changes in concentration of sulfate, dissolved oxygen, and H+ observed in the lab-scale experiments were qualitatively reproduced by the models applying the same boundary conditions on a site-scale. This integrated study acknowledged that the combination of experiments and models is a powerful tool to prognose the geochemical consequences of gas leakage on site scale. However, it is yet unknown how the passivation would be effected if the carbonate buffer depleted on the long term and under what circumstances a transition from the passivating pyrite oxidation process to the non-passivating process observed for instance in acid mine drainage setups occurs. These restrictions mark the limits of validity of our experimental and modeling concept. This conclusion suggests the feasibility of the presented integrated approach also when evaluating comparable scenarios on methane and hydrogen storage based on experimental results gathered similarly[2]. [1]Berta et al. Environ Earth Sci (2016) 75:1175, DOI 10.1007/s12665-016-5985-7. [2]Berta et al. First Break (2015) 33,93-95, ISSN 1365-2397. This work is part of the ANGUS+ project funded by the BMBF-FK03EK3022.

Site Preference of Ternary Alloying Additions to AuTi

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Mosca, Hugo O.; Noebe, Ronald D.

2006-01-01

Atomistic modeling of the site substitution behavior of several alloying additions, namely. Na, Mg, Al, Si. Sc, V, Cr, Mn. Fe, Co, Ni, Cu, Zn, Y, Zr. Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, and Pt in B2 TiAu is reported. The 30 elements can be grouped according to their absolute preference for a specific site, regardless of concentration, or preference for available sites in the deficient sublattice. Results of large scale simulations are also presented, distinguishing between additions that remain in solution from those that precipitate a second phase.

Application of Watershed Scale Models to Predict Nitrogen Loading From Coastal Plain Watersheds

Treesearch

George M. Chescheir; Glenn P Fernandez; R. Wayne Skaggs; Devendra M. Amatya

2004-01-01

DRAINMOD-based watershed models have been developed and tested using data collected from an intensively instrumented research site on Kendricks Creek watershed near Plymouth. NC. These models were applied to simulate the hydrology and nitrate nitrogen (NO3-N) loading from two other watersheds in the Coastal Plain of North Carolina, the 11600 ha Chicod Creek watershed...

Development of a zoning-based environmental-ecological-coupled model for lakes to assess lake restoration effect

NASA Astrophysics Data System (ADS)

Xu, Mengjia; Zou, Changxin; Zhao, Yanwei

2017-04-01

Environmental/ecological models are widely used for lake management as they provide a means to understand physical, chemical and biological processes in highly complex ecosystems. Most research focused on the development of environmental (water quality) and ecological models, separately. Limited studies were developed to couple the two models, and in these limited coupled models, a lake was regarded as a whole for analysis (i.e., considering the lake to be one well-mixed box), which was appropriate for small-scale lakes and was not sufficient to capture spatial variations within middle-scale or large-scale lakes. This paper seeks to establish a zoning-based environmental-ecological-coupled model for a lake. The Baiyangdian Lake, the largest freshwater lake in Northern China, was adopted as the study case. The coupled lake models including a hydrodynamics and water quality model established by MIKE21 and a compartmental ecological model used STELLA software have been established for middle-sized Baiyangdian Lake to realize the simulation of spatial variations of ecological conditions. On the basis of the flow field distribution results generated by MIKE21 hydrodynamics model, four water area zones were used as an example for compartmental ecological model calibration and validation. The results revealed that the developed coupled lake models can reasonably reflected the changes of the key state variables although there remain some state variables that are not well represented by the model due to the low quality of field monitoring data. Monitoring sites in a compartment may not be representative of the water quality and ecological conditions in the entire compartment even though that is the intention of compartment-based model design. There was only one ecological observation from a single monitoring site for some periods. This single-measurement issue may cause large discrepancies particularly when sampled site is not representative of the whole compartment. The coupled models have been applied to simulate the spatial variation trends of ecological condition under ecological water supplement as an example to reflect the application effect in lake restoration and management. The simulation results indicate that the models can provide a useful tool for lake restoration and management. The simulated spatial variation trends can provide a foundation for establishing permissible ranges for a selected set of water quality indices for a series of management measures such as watershed pollution load control and ecological water transfer. Meanwhile, the coupled models can help us to understand processes taking place and the relations of interaction between components in the lake ecosystem and external conditions. Taken together, the proposed models we established show some promising applications as middle-scale or large-scale lake management tools for pollution load control and ecological water transfer. These tools quantify the implications of proposed future water management decisions.

Inverse modeling of BTEX dissolution and biodegradation at the Bemidji, MN crude-oil spill site

USGS Publications Warehouse

Essaid, H.I.; Cozzarelli, I.M.; Eganhouse, R.P.; Herkelrath, W.N.; Bekins, B.A.; Delin, G.N.

2003-01-01

The U.S. Geological Survey (USGS) solute transport and biodegradation code BIOMOC was used in conjunction with the USGS universal inverse modeling code UCODE to quantify field-scale hydrocarbon dissolution and biodegradation at the USGS Toxic Substances Hydrology Program crude-oil spill research site located near Bemidji, MN. This inverse modeling effort used the extensive historical data compiled at the Bemidji site from 1986 to 1997 and incorporated a multicomponent transport and biodegradation model. Inverse modeling was successful when coupled transport and degradation processes were incorporated into the model and a single dissolution rate coefficient was used for all BTEX components. Assuming a stationary oil body, we simulated benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene (BTEX) concentrations in the oil and ground water, respectively, as well as dissolved oxygen. Dissolution from the oil phase and aerobic and anaerobic degradation processes were represented. The parameters estimated were the recharge rate, hydraulic conductivity, dissolution rate coefficient, individual first-order BTEX anaerobic degradation rates, and transverse dispersivity. Results were similar for simulations obtained using several alternative conceptual models of the hydrologic system and biodegradation processes. The dissolved BTEX concentration data were not sufficient to discriminate between these conceptual models. The calibrated simulations reproduced the general large-scale evolution of the plume, but did not reproduce the observed small-scale spatial and temporal variability in concentrations. The estimated anaerobic biodegradation rates for toluene and o-xylene were greater than the dissolution rate coefficient. However, the estimated anaerobic biodegradation rates for benzene, ethylbenzene, and m,p-xylene were less than the dissolution rate coefficient. The calibrated model was used to determine the BTEX mass balance in the oil body and groundwater plume. Dissolution from the oil body was greatest for compounds with large effective solubilities (benzene) and with large degradation rates (toluene and o-xylene). Anaerobic degradation removed 77% of the BTEX that dissolved into the water phase and aerobic degradation removed 17%. Although goodness-of-fit measures for the alternative conceptual models were not significantly different, predictions made with the models were quite variable. ?? 2003 Elsevier Science B.V. All rights reserved.

7Be and hydrological model for more efficient implementation of erosion control measure

NASA Astrophysics Data System (ADS)

Al-Barri, Bashar; Bode, Samuel; Blake, William; Ryken, Nick; Cornelis, Wim; Boeckx, Pascal

2014-05-01

Increased concern about the on-site and off-site impacts of soil erosion in agricultural and forested areas has endorsed interest in innovative methods to assess in an unbiased way spatial and temporal soil erosion rates and redistribution patterns. Hence, interest in precisely estimating the magnitude of the problem and therefore applying erosion control measures (ECM) more efficiently. The latest generation of physically-based hydrological models, which fully couple overland flow and subsurface flow in three dimensions, permit implementing ECM in small and large scales more effectively if coupled with a sediment transport algorithm. While many studies focused on integrating empirical or numerical models based on traditional erosion budget measurements into 3D hydrological models, few studies evaluated the efficiency of ECM on watershed scale and very little attention is given to the potentials of environmental Fallout Radio-Nuclides (FRNs) in such applications. The use of FRN tracer 7Be in soil erosion/deposition research proved to overcome many (if not all) of the problems associated with the conventional approaches providing reliable data for efficient land use management. This poster will underline the pros and cones of using conventional methods and 7Be tracers to evaluate the efficiency of coconuts dams installed as ECM in experimental field in Belgium. It will also outline the potentials of 7Be in providing valuable inputs for evolving the numerical sediment transport algorithm needed for the hydrological model on field scale leading to assess the possibility of using this short-lived tracer as a validation tool for the upgraded hydrological model on watershed scale in further steps. Keywords: FRN, erosion control measures, hydrological modes

Within-species patterns challenge our understanding of the causes and consequences of trait variation with implications for trait-based models

NASA Astrophysics Data System (ADS)

Anderegg, L. D.; Berner, L. T.; Badgley, G.; Hillerislambers, J.; Law, B. E.

2017-12-01

Functional traits could facilitate ecological prediction by provide scale-free tools for modeling ecosystem function. Yet much of their utility lies in three key assumptions: 1) that global patterns of trait covariation are the result of universal trade-offs independent of taxonomic scale, so empirical trait-trait relationships can be used to constrain vegetation models 2) that traits respond predictably to environmental gradients and can therefore be reliably quantified to parameterize models and 3) that well sampled traits influence productivity. We use an extensive dataset of within-species leaf trait variation in North American conifers combined with global leaf trait datasets to test these assumptions. We examine traits central to the `leaf economics spectrum', and quantify patterns of trait variation at multiple taxonomic scales. We also test whether site environment explains geographic trait variation within conifers, and ask whether foliar traits explain geographic variation in relative growth rates. We find that most leaf traits vary primarily between rather than within species globally, but that a large fraction of within-PFT trait variation is within-species. We also find that some leaf economics spectrum relationships differ in sign within versus between species, particularly the relationship between leaf lifespan and LMA. In conifers, we find weak and inconsistent relationships between site environment and leaf traits, making it difficult capture within-species leaf trait variation for regional model parameterization. Finally, we find limited relationships between tree relative growth rate and any foliar trait other than leaf lifespan, with leaf traits jointly explaining 42% of within-species growth variation but environmental factors explaining 77% of variation. We suggest that additional traits, particularly whole plant allometry/allocation traits may be better than leaf traits for improving vegetation model performance at smaller taxonomic and spatial scales.

Portable chamber measurements of evapotranspiration at the Amargosa Desert Research Site near Beatty, Nye County, Nevada, 2003-06

USGS Publications Warehouse

Garcia, C. Amanda; Johnson, Michael J.; Andraski, Brian J.; Halford, Keith J.; Mayers, C. Justin

2008-01-01

Portable chamber measurements of evapotranspiration (ET) were made at the U.S. Geological Survey's Amargosa Desert Research Site in southern Nevada to help quantify component- and landscape-scale contributions to ET in an arid environment. Evapotranspiration data were collected approximately every 3 months from 2003 to 2006. Chamber measurements of ET were partitioned into bare-soil evaporation and mixed-species transpiration components. The component-scale ET fluxes from native shrubs typically surpassed those from bare soil by as much as a factor of four. Component-scale ET fluxes were extrapolated to landscape-scale ET using a one-layer, multi-component canopy model. Landscape-scale ET fluxes predominantly were controlled by bare-soil evaporation. Bare soil covered 94 percent of the landscape on average and contributed about 70 percent of the landscape-scale vapor flux. Creosote bush, an evergreen shrub, accounted for about 90 percent of transpiration on average due to its dominance across the landscape (80 percent of the 6 percent shrub cover) and evergreen character.

Linking Arctic plant biodiversity measurements with landscape heterogeneity

NASA Astrophysics Data System (ADS)

Gerber, F.; Schaepman-Strub, G.; Furrer, R.

2016-12-01

Climate warming in the Arctic region triggers changes in the vegetation productivity and species composition of the tundra. To investigate these changes and their feedback to climate, we consider species richness and abundance data of the International Tundra EXperiment (ITEX). As this information is very sparse in time and space, we aim to upscale available records to climatically relevant scales with a remote sensing based characterization of the study sites. More precisely, we relate species richness and evenness derived from the ITEX data to summary statistics describing the landscape heterogeneity, which are derived from an elevation model (ASTER GDEM) and spectral satellite observations (LANDSAT 5 and 7). Preliminary results from the statistical analysis using generalized linear mixed models show that no remote sensing based landscape characterization does significantly explain species richness. Reasons could be a mismatch of the spatial scales, an inappropriate characterization of the test sites through the satellite measurements, incomparable plot measurements from the different test sites and/or too few plot measurements. We are looking forward to presenting our results and getting your inputs.

Surface and subsurface geologic risk factors to ground water affecting brownfield redevelopment potential.

PubMed

Kaufman, Martin M; Murray, Kent S; Rogers, Daniel T

2003-01-01

A model is created for assessing the redevelopment potential of brownfields. The model is derived from a space and time conceptual framework that identifies and measures the surface and subsurface risk factors present at brownfield sites. The model then combines these factors with a contamination extent multiplier at each site to create an index of redevelopment potential. Results from the application of the model within an urbanized watershed demonstrate clear differences between the redevelopment potential present within five different near-surface geologic units, with those units containing clay being less vulnerable to subsurface contamination. With and without the extent multiplier, the total risk present at the brownfield sites within all the geologic units is also strongly correlated to the actual costs of remediation. Thus, computing the total surface and subsurface risk within a watershed can help guide the remediation efforts at broad geographic scales, and prioritize the locations for redevelopment.

A Regional Atmospheric Continuous CO2 Network In The Rocky Mountains (Rocky RACCOON)

NASA Astrophysics Data System (ADS)

Stephens, B.; de Wekker, S.; Watt, A.; Schimel, D.

2005-12-01

We have established a continuous CO2 observing network in the Rocky Mountains, building on technological and modeling advances made during the Carbon in the Mountains Experiment (CME), to improve our understanding of regional carbon fluxes and to fill key gaps in the North American Carbon Program (NACP). We will present a description of the Rocky RACCOON network and early results from the first three sites. There are strong scientific and societal motivations for determining CO2 exchanges on regional scales. NACP aims to address these concerns through a dramatic expansion in observations and modeling capabilities over North America. Mountain forests in particular represent a significant potential net CO2 sink in the U.S. and are highly sensitive to land-use practices and climate change. However, plans for new continuous CO2 observing sites have omitted the mountain west. This resulted from expensive instrumentation in the face of limited resources, and a perception that current atmospheric transport models are not sophisticated enough to interpret CO2 measurements made in complex terrain. Through our efforts in CME, we have a new autonomous, inexpensive, and robust CO2 analysis system and are developing mountain CO2 modeling tools that will help us to overcome these obstacles. Preliminary observational and modeling results give us confidence that continuous CO2 observations from mountain top observatories will provide useful constraints on regional carbon cycling and will be valuable in the continental inverse modeling efforts planned for NACP. We began at three Colorado sites in August 2005 and hope to add three to six sites in other western states in subsequent years, utilizing existing observatories to the maximum extent possible. The first three sites are at Niwot Ridge, allowing us to have an ongoing intercomparison with flask measurements made by NOAA CMDL; at Storm Peak Laboratory near Steamboat Springs, allowing us to investigate comparisons between these two relatively nearby sites; and at Fraser Experimental Forest, allowing us to investigate nocturnal respiration rates across a large intermountain valley. Our data are available to the public on the internet in near real time to support quality control, local science, and larger scale synthesis efforts.

FIELD INVESTIGATIONS OF THE DRIFT SHADOW

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. W. Su, T. J. Kneafsey, T. A. Ghezzehei, B. D. Marshall, and P. J. Cook

The ''Drift Shadow'' is defined as the relatively drier region that forms below subsurface cavities or drifts in unsaturated rock. Its existence has been predicted through analytical and numerical models of unsaturated flow. However, these theoretical predictions have not been demonstrated empirically to date. In this project they plan to test the drift shadow concept through field investigations and compare our observations to simulations. Based on modeling studies they have an identified suitable site to perform the study at an inactive mine in a sandstone formation. Pretest modeling studies and preliminary characterization of the site are being used to developmore » the field scale tests.« less

A Hydrostratigraphic System for Modeling Groundwater Flow and Radionuclide Migration at the Corrective Action Unit Scale, Nevada Test Site and Surrounding Areas, Clark, Lincoln, and Nye Counties, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prothro, Lance; Drellack Jr., Sigmund; Mercadante, Jennifer

2009-01-31

Underground Test Area (UGTA) corrective action unit (CAU) groundwater flow and contaminant transport models of the Nevada Test Site (NTS) and vicinity are built upon hydrostratigraphic framework models (HFMs) that utilize the hydrostratigraphic unit (HSU) as the fundamental modeling component. The delineation and three-dimensional (3-D) modeling of HSUs within the highly complex geologic terrain that is the NTS requires a hydrostratigraphic system that is internally consistent, yet flexible enough to account for overlapping model areas, varied geologic terrain, and the development of multiple alternative HFMs. The UGTA CAU-scale hydrostratigraphic system builds on more than 50 years of geologic and hydrologicmore » work in the NTS region. It includes 76 HSUs developed from nearly 300 stratigraphic units that span more than 570 million years of geologic time, and includes rock units as diverse as marine carbonate and siliciclastic rocks, granitic intrusives, rhyolitic lavas and ash-flow tuffs, and alluvial valley-fill deposits. The UGTA CAU-scale hydrostratigraphic system uses a geology-based approach and two-level classification scheme. The first, or lowest, level of the hydrostratigraphic system is the hydrogeologic unit (HGU). Rocks in a model area are first classified as one of ten HGUs based on the rock’s ability to transmit groundwater (i.e., nature of their porosity and permeability), which at the NTS is mainly a function of the rock’s primary lithology, type and degree of postdepositional alteration, and propensity to fracture. The second, or highest, level within the UGTA CAU-scale hydrostratigraphic system is the HSU, which is the fundamental mapping/modeling unit within UGTA CAU-scale HFMs. HSUs are 3-D bodies that are represented in the finite element mesh for the UGTA groundwater modeling process. HSUs are defined systematically by stratigraphically organizing HGUs of similar character into larger HSUs designations. The careful integration of stratigraphic information in the development of HSUs is important to assure individual HSUs are internally consistent, correlatable, and mappable throughout all the model areas.« less

Interests of hydrogeological observatories for characterizing heterogeneous groundwater systems: the example of the Ploemeur hard-rock aquifer (French Brittany)

NASA Astrophysics Data System (ADS)

Bour, O.; Le Borgne, T.; Aquilina, L.; Labasque, T.; Lavenant, N.; Boudin, F.; Leray, S.; De Dreuzy, J.; Longuevergne, L.; Hochreutener, R.; Davy, P.

2012-12-01

Heterogeneous aquifers are often poorly constrained by the available data. There is a strong need of characterizing at multiple space and time scales heterogeneous groundwater systems to improve model predictions. Here, we present results from the site of Ploemeur (French Brittany) that belongs to the network of hydrogeological sites H+, and where complementarity approaches have been developed for almost fifteen years. This outstandingly heterogeneous crystalline rock aquifer is used for water supply at a rate of about 10^6 m3 per year since 1991. The geology of the area is relatively complex and involves two main structures: a highly fractured contact zone between the Ploemeur's granite and the overlying micaschists, and a steeply dipping fault striking North 20°. The contact zone in itself consists of alternating deformed granitic sheets and enclaves of micaschists, pegmatite and aplite dykes, and locally mylonites and pegmatite-bearing breccias that are often associated with major borehole inflows. At the site scale - typically a square kilometer - and at relatively shallow depth (100 to 150 m), the connectivity of the main flow paths and the hydraulic properties are relatively well constrained and quantified thanks to cross-borehole flowmeter tests and traditional pumping tests. However, such data are relatively limited in explaining the functioning of this confined groundwater system at the regional scale. Groundwater chemistry and groundwater dating permit to go further to identify distinct reservoirs and in particular a relatively deep groundwater component whose age is older than 50 years. Groundwater temperature measurements demonstrate the role of the pumping that influences greatly the spatial distribution of groundwater temperature and quality. Moreover, it suggests that the main water supply comes from a depth of at least 300 meters. This implies relatively deep groundwater circulation that can be achieved only thanks to major permeable fault zone. At the watershed scale - typically ten square kilometers - we show through a high-resolution gravimetric survey that the highly fractured contact between granite and micaschists, which constitutes the main path for groundwater flow, is a gently dipping structure towards the North. This is consistent with measurements of the ground surface deformation through long-base tiltmeters, which suggest that recharge of the aquifer come from the North. Finally, a numerical model of the site that combines hydraulic and age information confirms the geometry of the major permeable fault zone and the consistency of the different datasets. The Ploemeur example shows how multiple datasets at different scales may be combined to characterize and model heterogeneous groundwater systems. It also shows the interests of using specific sites as hydrogeological observatories to test novel field methods, to evaluate the relevance of numerical and theoretical models, to monitor groundwater changes and to improve our knowledge on groundwater systems.

Reach and catchment-scale characteristics are relatively uninfluential in explaining the occurrence of stream fish species.

PubMed

Wuellner, M R; Bramblett, R G; Guy, C S; Zale, A V; Roberts, D R; Johnson, J

2013-05-01

The objectives of this study were (1) to determine whether the presence or absence of prairie fishes can be modelled using habitat and biotic characteristics measured at the reach and catchment scales and (2) to identify which scale (i.e. reach, catchment or a combination of variables measured at both scales) best explains the presence or absence of fishes. Reach and catchment information from 120 sites sampled from 1999 to 2004 were incorporated into tree classifiers for 20 prairie fish species, and multiple criteria were used to evaluate models. Fewer than six models were considered significant when modelling individual fish occurrences at the reach, catchment or combined scale, and only one species was successfully modelled at all three scales. The scarcity of significant models is probably related to the rigorous criteria by which these models were evaluated as well as the prevalence of tolerant, generalist fishes in these stochastic and intermittent streams. No significant differences in the amount of reduced deviance, mean misclassification error rates (MER), and mean improvement in MER metrics was detected among the three scales. Results from this study underscore the importance of continued habitat assessment at smaller scales to further understand prairie-fish occurrences as well as further evaluations of modelling methods to examine habitat relationships for tolerant, ubiquitous species. Incorporation of such suggestions in the future may help provide more accurate models that will allow for better management and conservation of prairie-fish species. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

The seasonal behaviour of carbon fluxes in the Amazon: fusion of FLUXNET data and the ORCHIDEE model

NASA Astrophysics Data System (ADS)

Verbeeck, H.; Peylin, P.; Bacour, C.; Ciais, P.

2009-04-01

Eddy covariance measurements at the Santarém (km 67) site revealed an unexpected seasonal pattern in carbon fluxes which could not be simulated by existing state-of-the-art global ecosystem models (Saleska et al., Sciece 2003). An unexpected high carbon uptake was measured during dry season. In contrast, carbon release was observed in the wet season. There are several possible (combined) underlying mechanisms of this phenomenon: (1) an increased soil respiration due to soil moisture in the wet season, (2) increased photosynthesis during the dry season due to deep rooting, hydraulic lift, increased radiation and/or a leaf flush. The objective of this study is to optimise the ORCHIDEE model using eddy covariance data in order to be able to mimic the seasonal response of carbon fluxes to dry/wet conditions in tropical forest ecosystems. By doing this, we try to identify the underlying mechanisms of this seasonal response. The ORCHIDEE model is a state of the art mechanistic global vegetation model that can be run at local or global scale. It calculates the carbon and water cycle in the different soil and vegetation pools and resolves the diurnal cycle of fluxes. ORCHIDEE is built on the concept of plant functional types (PFT) to describe vegetation. To bring the different carbon pool sizes to realistic values, spin-up runs are used. ORCHIDEE uses climate variables as drivers together with a number of ecosystem parameters that have been assessed from laboratory and in situ experiments. These parameters are still associated with a large uncertainty and may vary between and within PFTs in a way that is currently not informed or captured by the model. Recently, the development of assimilation techniques allows the objective use of eddy covariance data to improve our knowledge of these parameters in a statistically coherent approach. We use a Bayesian optimisation approach. This approach is based on the minimization of a cost function containing the mismatch between simulated model output and observations as well as the mismatch between a priori and optimized parameters. The parameters can be optimized on different time scales (annually, monthly, daily). For this study the model is optimised at local scale for 5 eddy flux sites: 4 sites in Brazil and one in French Guyana. The seasonal behaviour of C fluxes in response to wet and dry conditions differs among these sites. Key processes that are optimised include: the effect of the soil water on heterotrophic soil respiration, the effect of soil water availability on stomatal conductance and photosynthesis, and phenology. By optimising several key parameters we could improve the simulation of the seasonal pattern of NEE significantly. Nevertheless, posterior parameters should be interpreted with care, because resulting parameter values might compensate for uncertainties on the model structure or other parameters. Moreover, several critical issues appeared during this study e.g. how to assimilate latent and sensible heat data, when the energy balance is not closed in the data? Optimisation of the Q10 parameter showed that on some sites respiration was not sensitive at all to temperature, which show only small variations in this region. Considering this, one could question the reliability of the partitioned fluxes (GPP/Reco) at these sites. This study also tests if there is coherence between optimised parameter values of different sites within the tropical forest PFT and if the forward model response to climate variations is similar between sites.

Effect of climate change on environmental flow indicators in the narew basin, poland.

PubMed

Piniewski, Mikołaj; Laizé, Cédric L R; Acreman, Michael C; Okruszko, Tomasz; Schneider, Christof

2014-01-01

Environmental flows-the quantity of water required to maintain a river ecosystem in its desired state-are of particular importance in areas of high natural value. Water-dependent ecosystems are exposed to the risk of climate change through altered precipitation and evaporation. Rivers in the Narew basin in northeastern Poland are known for their valuable river and wetland ecosystems, many of them in pristine or near-pristine condition. The objective of this study was to assess changes in the environmental flow regime of the Narew river system, caused by climate change, as simulated by hydrological models with different degrees of physical characterization and spatial aggregation. Two models were assessed: the river basin scale model Soil and Water Assessment Tool (SWAT) and the continental model of water availability and use WaterGAP. Future climate change scenarios were provided by two general circulation models coupled with the A2 emission scenario: IPSL-CM4 and MIROC3.2. To assess the impact of climate change on environmental flows, a method based conceptually on the "range of variability" approach was used. The results indicate that the environmental flow regime in the Narew basin is subject to climate change risk, whose magnitude and spatial variability varies with climate model and hydrological modeling scale. Most of the analyzed sites experienced moderate impacts for the Generic Environmental Flow Indicator (GEFI), the Floodplain Inundation Indicator, and the River Habitat Availability Indicator. The consistency between SWAT and WaterGAP for GEFI was medium: in 55 to 66% of analyzed sites, the models suggested the same level of impact. Hence, we suggest that state-of-the-art, high-resolution, global- or continental-scale models, such as WaterGAP, could be useful tools for water management decision-makers and wetland conservation practitioners, whereas models such as SWAT should serve as a complementary tool for more specific, smaller-scale, local assessments. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Ensemble modeling to predict habitat suitability for a large-scale disturbance specialist

Treesearch

Quresh S. Latif; Victoria A. Saab; Jonathan G. Dudley; Jeff P. Hollenbeck

2013-01-01

To conserve habitat for disturbance specialist species, ecologists must identify where individuals will likely settle in newly disturbed areas. Habitat suitability models can predict which sites at new disturbances will most likely attract specialists. Without validation data from newly disturbed areas, however, the best approach for maximizing predictive accuracy can...

An Integrated Modeling Framework for Performing Environmental Assessments: Application to Ecosystem Services in the Albemarle-Pamlico Basins (NC and VA,USA)

EPA Science Inventory

The U.S. Environmental Protection Agency uses environmental models to inform rulemaking and policy decisions at multiple spatial and temporal scales. As decision-making has moved towards integrated thinking and assessment (e.g. media, site, region, services), the increasing compl...

Evaluation of the removal of Strontium-90 from groundwater using a zeolite rich-rock permeable treatment wall

NASA Astrophysics Data System (ADS)

Seneca, S. M.; Rabideau, A. J.; Bandilla, K.

2010-12-01

Experimental and modeling studies are in progress to evaluate the long-term performance of a permeable treatment wall comprised of zeolite-rich rock for the removal of strontium-90 from groundwater. Multiple column tests were performed at the University at Buffalo and on-site West Valley Environmental Services; columns were supplied with synthetic groundwater referenced to anticipate field conditions and radioactive groundwater on-site WVES. The primary focus in this work is on quantifying the competitive ion exchange among five cations (Na+, K+, Ca2+, Mg2+, and Sr2+); the data obtained from the column studies is used to support the robust estimation of zeolite cation exchange parameters. This research will produce a five-solute cation exchange model describing the removal efficiency of the zeolite, using the various column tests to calibrate and validate the geochemical transport model. The field-scale transport model provides flexibility to explore design parameters and potential variations in groundwater geochemistry to investigate the long-term performance of a full scale treatment wall at the Western New York nuclear facility.

Incorporating geologic information into hydraulic tomography: A general framework based on geostatistical approach

NASA Astrophysics Data System (ADS)

Zha, Yuanyuan; Yeh, Tian-Chyi J.; Illman, Walter A.; Onoe, Hironori; Mok, Chin Man W.; Wen, Jet-Chau; Huang, Shao-Yang; Wang, Wenke

2017-04-01

Hydraulic tomography (HT) has become a mature aquifer test technology over the last two decades. It collects nonredundant information of aquifer heterogeneity by sequentially stressing the aquifer at different wells and collecting aquifer responses at other wells during each stress. The collected information is then interpreted by inverse models. Among these models, the geostatistical approaches, built upon the Bayesian framework, first conceptualize hydraulic properties to be estimated as random fields, which are characterized by means and covariance functions. They then use the spatial statistics as prior information with the aquifer response data to estimate the spatial distribution of the hydraulic properties at a site. Since the spatial statistics describe the generic spatial structures of the geologic media at the site rather than site-specific ones (e.g., known spatial distributions of facies, faults, or paleochannels), the estimates are often not optimal. To improve the estimates, we introduce a general statistical framework, which allows the inclusion of site-specific spatial patterns of geologic features. Subsequently, we test this approach with synthetic numerical experiments. Results show that this approach, using conditional mean and covariance that reflect site-specific large-scale geologic features, indeed improves the HT estimates. Afterward, this approach is applied to HT surveys at a kilometer-scale-fractured granite field site with a distinct fault zone. We find that by including fault information from outcrops and boreholes for HT analysis, the estimated hydraulic properties are improved. The improved estimates subsequently lead to better prediction of flow during a different pumping test at the site.

Multiple scale dynamo

PubMed Central

Le Mouël, Jean-Louis; Allègre, Claude J.; Narteau, Clément

1997-01-01

A scaling law approach is used to simulate the dynamo process of the Earth’s core. The model is made of embedded turbulent domains of increasing dimensions, until the largest whose size is comparable with the site of the core, pervaded by large-scale magnetic fields. Left-handed or right-handed cyclones appear at the lowest scale, the scale of the elementary domains of the hierarchical model, and disappear. These elementary domains then behave like electromotor generators with opposite polarities depending on whether they contain a left-handed or a right-handed cyclone. To transfer the behavior of the elementary domains to larger ones, a dynamic renormalization approach is used. A simple rule is adopted to determine whether a domain of scale l is a generator—and what its polarity is—in function of the state of the (l − 1) domains it is made of. This mechanism is used as the main ingredient of a kinematic dynamo model, which displays polarity intervals, excursions, and reversals of the geomagnetic field. PMID:11038547

Modelling deep water habitats to develop a spatially explicit, fine scale understanding of the distribution of the western rock lobster, Panulirus cygnus.

PubMed

Hovey, Renae K; Van Niel, Kimberly P; Bellchambers, Lynda M; Pember, Matthew B

2012-01-01

The western rock lobster, Panulirus cygnus, is endemic to Western Australia and supports substantial commercial and recreational fisheries. Due to and its wide distribution and the commercial and recreational importance of the species a key component of managing western rock lobster is understanding the ecological processes and interactions that may influence lobster abundance and distribution. Using terrain analyses and distribution models of substrate and benthic biota, we assess the physical drivers that influence the distribution of lobsters at a key fishery site. Using data collected from hydroacoustic and towed video surveys, 20 variables (including geophysical, substrate and biota variables) were developed to predict the distributions of substrate type (three classes of reef, rhodoliths and sand) and dominant biota (kelp, sessile invertebrates and macroalgae) within a 40 km(2) area about 30 km off the west Australian coast. Lobster presence/absence data were collected within this area using georeferenced pots. These datasets were used to develop a classification tree model for predicting the distribution of the western rock lobster. Interestingly, kelp and reef were not selected as predictors. Instead, the model selected geophysical and geomorphic scalar variables, which emphasise a mix of terrain within limited distances. The model of lobster presence had an adjusted D(2) of 64 and an 80% correct classification. Species distribution models indicate that juxtaposition in fine scale terrain is most important to the western rock lobster. While key features like kelp and reef may be important to lobster distribution at a broad scale, it is the fine scale features in terrain that are likely to define its ecological niche. Determining the most appropriate landscape configuration and scale will be essential to refining niche habitats and will aid in selecting appropriate sites for protecting critical lobster habitats.

Modelling Deep Water Habitats to Develop a Spatially Explicit, Fine Scale Understanding of the Distribution of the Western Rock Lobster, Panulirus cygnus

PubMed Central

Hovey, Renae K.; Van Niel, Kimberly P.; Bellchambers, Lynda M.; Pember, Matthew B.

2012-01-01

Background The western rock lobster, Panulirus cygnus, is endemic to Western Australia and supports substantial commercial and recreational fisheries. Due to and its wide distribution and the commercial and recreational importance of the species a key component of managing western rock lobster is understanding the ecological processes and interactions that may influence lobster abundance and distribution. Using terrain analyses and distribution models of substrate and benthic biota, we assess the physical drivers that influence the distribution of lobsters at a key fishery site. Methods and Findings Using data collected from hydroacoustic and towed video surveys, 20 variables (including geophysical, substrate and biota variables) were developed to predict the distributions of substrate type (three classes of reef, rhodoliths and sand) and dominant biota (kelp, sessile invertebrates and macroalgae) within a 40 km2 area about 30 km off the west Australian coast. Lobster presence/absence data were collected within this area using georeferenced pots. These datasets were used to develop a classification tree model for predicting the distribution of the western rock lobster. Interestingly, kelp and reef were not selected as predictors. Instead, the model selected geophysical and geomorphic scalar variables, which emphasise a mix of terrain within limited distances. The model of lobster presence had an adjusted D2 of 64 and an 80% correct classification. Conclusions Species distribution models indicate that juxtaposition in fine scale terrain is most important to the western rock lobster. While key features like kelp and reef may be important to lobster distribution at a broad scale, it is the fine scale features in terrain that are likely to define its ecological niche. Determining the most appropriate landscape configuration and scale will be essential to refining niche habitats and will aid in selecting appropriate sites for protecting critical lobster habitats. PMID:22506021

Drivers of spatial heterogeneity in nitrogen processing among three alpine plant communities in the Rocky Mountains

NASA Astrophysics Data System (ADS)

Churchill, A. C.; Beers, A.; Grinath, J.; Bowman, W. D.

2017-12-01

Nitrogen cycling across the globe has been fundamentally altered due to regional elevated N deposition and there is a cascade of ecosystem consequences including shifts in species composition, eutrophication, and soil acidification. Making predictions that encompass the factors that drive these ecosystem changes has frequently been limited to single ecosystem types, or areas with fairly homogenous abiotic conditions. The alpine is an ecosystem type that exhibits changes under relatively low levels of N depositions due to short growing seasons and shallow soils limiting N storage. While recent work provided estimates for the magnitude of N associated with ecosystem changes, less is known about the within-site factors that may interact to stabilize or amplify the differential response of N pools under future conditions of resource deposition. To examine numerous potential within-site and regional factors (both biotic and abiotic) affecting ecosystem N pools we examined the relationship between those factors and a suite of ecosystem pools of N followed by model selection procedures and structural equation modelling. Measurements were conducted at Niwot Ridge Long Term Ecological Research site and in Rocky Mountain National Park in three distinct alpine meadow ecosystems (dry, moist, and wet meadows). These meadows span a moisture gradient as well as plant community composition, thereby providing high variability of potential biotic and abiotic drivers across small spatial scales in the alpine. In general, regional scale abiotic factors such as site levels of annual average N deposition or precipitation were poor predictors of seasonal pools of N, while spring soil water pools of N were negatively correlated with elevation. Models containing multiple abiotic and biotic drivers, however, were best at predicting soil and plant pools of N across the two sites. Future analysis will include highlight interactions among with-site factors affecting N pools in the alpine using structural equation modelling to statistically examine the bidirectional relationship between plant communities and soil pools of N.

Analytical model for the design of in situ horizontal permeable reactive barriers (HPRBs) for the mitigation of chlorinated solvent vapors in the unsaturated zone

NASA Astrophysics Data System (ADS)

Verginelli, Iason; Capobianco, Oriana; Hartog, Niels; Baciocchi, Renato

2017-02-01

In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a second-order reaction rate constant. Furthermore, the model accounts for the HPRB lifetime as a function of the oxidant consumption by reaction with upward vapors and its progressive dissolution and leaching by infiltrating water. Simulation results by this new model closely replicate previous lab-scale tests carried out on trichloroethylene (TCE) using a HPRB containing a mixture of potassium permanganate, water and sand. In view of field applications, design criteria, in terms of the minimum HPRB thickness required to attenuate vapors at acceptable risk-based levels and the expected HPRB lifetime, are determined from site-specific conditions such as vapor source concentration, water infiltration rate and HPRB mixture. The results clearly show the field-scale feasibility of this alternative vapor mitigation system for the treatment of chlorinated solvents. Depending on the oxidation kinetic of the target contaminant, a 1 m thick HPRB can ensure an attenuation of vapor concentrations of orders of magnitude up to 20 years, even for vapor source concentrations up to 10 g/m3. A demonstrative application for representative contaminated site conditions also shows the feasibility of this mitigation system from an economical point of view with capital costs potentially somewhat lower than those of other remediation options, such as soil vapor extraction systems. Overall, based on the experimental and theoretical evaluation thus far, field-scale tests are warranted to verify the potential and cost-effectiveness of HPRBs for vapor mitigation control under various conditions of application.

VizieR Online Data Catalog: Equivalent width of 21 RR Lyrae stars (Pancino+, 2015)

NASA Astrophysics Data System (ADS)

Pancino, E.; Britavskiy, N.; Romano, D.; Cacciari, C.; Mucciarelli, A.; Clementini, G.

2015-02-01

Equivalent widths and atomic data of the absorption lines used in the abundance analysis, for each separate exposure at different phases. Observations of 15 RR Lyrae stars (DR And, X Ari, TW Boo, RZ Cam, RX Cet, U Com, RV CrB, SW CVn, UZ CVn, AE Dra, SZ Gem, VX Her, DH Hya, TU UMa, and RV UMa) and one BL Her star (UY Eri) were carried out with SARG@TNG, operated on the island of La Palma, Spain, during two separate runs in 2009 March and between September and November. Eight stars (SW Aqr, TW Cap, DH Hya, V Ind, SS Leo, V716 Oph, BK Tuc, and UV Vir) were observed with UVES@VLT, between 2009 April and August in service mode. (3 data files).

Resolute Apt, Northwest Territories, Canada. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

DTIC Science & Technology

1972-01-17

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Applicability of SREM to the Verification of Management Information System Software Requirements. Volume II.

DTIC Science & Technology

1981-04-30

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Prime Contract Awards of $100,000 or More by Federal Supply Classification or Service Category and Purchasing Office, FY 88. Part 1. (1005-5530).

DTIC Science & Technology

1988-01-01

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Global Magnetosphere Modeling With Kinetic Treatment of Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Toth, G.; Chen, Y.; Gombosi, T. I.; Cassak, P.; Markidis, S.; Peng, B.; Henderson, M. G.

2017-12-01

Global magnetosphere simulations with a kinetic treatment of magnetic reconnection are very challenging because of the large separation of global and kinetic scales. We have developed two algorithms that can overcome these difficulties: 1) the two-way coupling of the global magnetohydrodynamic code with an embedded particle-in-cell model (MHD-EPIC) and 2) the artificial increase of the ion and electron kinetic scales. Both of these techniques improve the efficiency of the simulations by many orders of magnitude. We will describe the techniques and show that they provide correct and meaningful results. Using the coupled model and the increased kinetic scales, we will present global magnetosphere simulations with the PIC domains covering the dayside and/or tail reconnection sites. The simulation results will be compared to and validated with MMS observations.

An ecodesign method for reducing the effects of hazardous substances in the product lifecycle

NASA Astrophysics Data System (ADS)

Simanovska, J.; Valters, K.; Bažbauers, G.; Luttropp, C.

2012-10-01

Growing evidence on the indoor and outdoor pollution caused by the flow of man-made products urges that the content and leaching of hazardous substances from products be minimised. One of the ways to reduce the potential adverse impacts caused by these substances could be via ecodesign - i.e. through the consideration of lifecycle-related environmental aspects during the product development. The authors’ review of the existing ecodesign methods highlights the weakness of these methods in identifying and assessing the health-related and environmental impacts of hazardous substances contained in products, especially with regard to the exposure assessment. Therefore, a new, semi-quantitative screening ecodesign method applicable for different types of products has been developed. The method ranks the most severe hazards based on the classification according to the Globally Harmonised System together with the exposure evaluation as well as integrates the aspects of material efficiency. This method is suitable for use in the product development process, requiring decisions to be made based on limited information while integrating the main principles of a scientific risk assessment for chemicals. Application of the method is demonstrated with a case study on products made of plywood. The method makes it possible to identify the needs for and elaboration of ecodesign proposals, and fosters communication and information exchange throughout the supply chain. Augošs pierādījumu daudzums par produktu sastāvā esošo kaitīgo ķīmisko vielu nelabvēlīgo ietekmi uz vidi un cilvēku veselību liecina par nepieciešamību samazināt šādu vielu saturu produktos un izdalīšanos no tiem, ko varētu realizēt ar ekodizaina palīdzību. Pārskatot zinātniskās publikācijas ekodizaina jomā, konstatēts, ka pašreiz ekodizaina metodes nepilnīgi nodrošina materiālu sastāvā esošo vielu kaitīgās ietekmes uz cilvēku veselību un apkārtējo vidi novēršanu. Tāpēc radīta jauna, daļēji kvantitatīva ekodizaina metode, apvienojot produktu izstrādes prasības ar zinātniskā ķīmiskā riska novērtēšanas principiem, kas piedāvā bīstamo īpašību prioritizēšanu, izmantojot Globāli harmonizētās sistēmas ķīmisko vielu klasifikācijas kodus, kā arī iedarbības un materiālu efektivitātes aspektu prioritizēšanu. Metode tika aprobēta, demonstrējot tās izmantošanu. Metode ļauj produkta izstrādātājam identificēt pārmaiņu nepieciešamību, izstrādāt ekodizaina priekšlikumus, izvērtēt alternatīvas, un palīdz uzlabot saziņu par materiālu īpašībām un ietekmi uz vidi un cilvēka veselību izejvielu un produktu piegādes ķēdē.

Prediction of biological integrity based on environmental similarity--revealing the scale-dependent link between study area and top environmental predictors.

PubMed

Bedoya, David; Manolakos, Elias S; Novotny, Vladimir

2011-03-01

Indices of Biological integrity (IBI) are considered valid indicators of the overall health of a water body because the biological community is an endpoint within natural systems. However, prediction of biological integrity using information from multi-parameter environmental observations is a challenging problem due to the hierarchical organization of the natural environment, the existence of nonlinear inter-dependencies among variables as well as natural stochasticity and measurement noise. We present a method for predicting the Fish Index of Biological Integrity (IBI) using multiple environmental observations at the state-scale in Ohio. Instream (chemical and physical quality) and offstream parameters (regional and local upstream land uses, stream fragmentation, and point source density and intensity) are used for this purpose. The IBI predictions are obtained using the environmental site-similarity concept and following a simple to implement leave-one-out cross validation approach. An IBI prediction for a sampling site is calculated by averaging the observed IBI scores of observations clustered in the most similar branch of a dendrogram--a hierarchical clustering tree of environmental observations--built using the rest of the observations. The standardized Euclidean distance is used to assess dissimilarity between observations. The constructed predictive model was able to explain 61% of the IBI variability statewide. Stream fragmentation and regional land use explained 60% of the variability; the remaining 1% was explained by instream habitat quality. Metrics related to local land use, water quality, and point source density and intensity did not improve the predictive model at the state-scale. The impact of local environmental conditions was evaluated by comparing local characteristics between well- and mispredicted sites. Significant differences in local land use patterns and upstream fragmentation density explained some of the model's over-predictions. Local land use conditions explained some of the model's IBI under-predictions at the state-scale since none of the variables within this group were included in the best final predictive model. Under-predicted sites also had higher levels of downstream fragmentation. The proposed variables ranking and predictive modeling methodology is very well suited for the analysis of hierarchical environments, such as natural fresh water systems, with many cross-correlated environmental variables. It is computationally efficient, can be fully automated, does not make any pre-conceived assumptions on the variables interdependency structure (such as linearity), and it is able to rank variables in a database and generate IBI predictions using only non-parametric easy to implement hierarchical clustering. Copyright © 2011 Elsevier Ltd. All rights reserved.

Lava flow topographic measurements for radar data interpretation

NASA Technical Reports Server (NTRS)

Campbell, Bruce A.; Garvin, James B.

1993-01-01

Topographic profiles at 25- and 5-cm horizontal resolution for three sites along a lava flow on Kilauea Volcano are presented, and these data are used to illustrate techniques for surface roughness analysis. Height and slope distributions and the height autocorrelation function are evaluated as a function of varying lowpass filter wavelength for the 25-cm data. Rms slopes are found to increase rapidly with decreasing topographic scale and are typically much higher than those found by modeling of Magellan altimeter data for Venus. A more robust description of the surface roughness appears to be the ratio of rms height to surface height correlation length. For all three sites this parameter falls within the range of values typically found from model fits to Magellan altimeter waveforms. The 5-cm profile data are used to estimate the effect of small-scale roughness on quasi-specular scattering.

Need for improved methods to collect and present spatial epidemiologic data for vectorborne diseases.

PubMed

Eisen, Lars; Eisen, Rebecca J

2007-12-01

Improved methods for collection and presentation of spatial epidemiologic data are needed for vectorborne diseases in the United States. Lack of reliable data for probable pathogen exposure site has emerged as a major obstacle to the development of predictive spatial risk models. Although plague case investigations can serve as a model for how to ideally generate needed information, this comprehensive approach is cost-prohibitive for more common and less severe diseases. New methods are urgently needed to determine probable pathogen exposure sites that will yield reliable results while taking into account economic and time constraints of the public health system and attending physicians. Recent data demonstrate the need for a change from use of the county spatial unit for presentation of incidence of vectorborne diseases to more precise ZIP code or census tract scales. Such fine-scale spatial risk patterns can be communicated to the public and medical community through Web-mapping approaches.

Landscape-Scale Soil Carbon Inventories by Microclimate Decomposition

NASA Astrophysics Data System (ADS)

Beaudette, D. E.; O'Geen, A. T.

2008-12-01

Estimation of carbon stocks in rangeland and foothill ecosystems is poised to become an important service once legislation regulating greenhouse gas emissions is passed. Trading of carbon credits and greenhouse gas emission/sequestration budgets for vegetated areas is largely dependent on an accurate and scale- dependent inventory of existing conditions. Soil survey presents one possible resource for surface carbon stocks, however these data are usually not mapped at the landscape-scale. Soil-landscape modeling techniques have been successfully used in several instances to predict the spatial variation in soil carbon. Most of these studies have used site exposure (aspect angle) as a categorical proxy for terrain-induced microclimate. Our objective was to model parameters related to soil microclimate (soil temperature and moisture) for the production of detailed maps of soil carbon and organic matter quality (i.e. C:N ratio). We used a solar radiation model and long-term monitoring of soil moisture and temperature to generate several models of soil microclimate. Parameterization of the ESRA (European Solar Radiation Atlas) solar radiation model (clear-sky version) was accomplished with daily estimates of the Linke turbidity factor, using local pyranometer measurements (11 year record). Our estimated daily radiance values correlated well with local weather station data (R2 = 0.965, p < 0.001). This model is included in the popular, open source GRASS GIS. A preliminary study based on 35 sites, spanning two contrasting landform types (and lithology), revealed a statistically significant relationship between annual radiation load and carbon (R2 = 0.75, p < 0.001). A highly significant relationship between C:N ratio and annual radiation load was identified as well (R2 = 0.99, p < 0.001). Solar radiation models are simple to use, and have the potential to refine previous soil-landscape modeling efforts that relied on aspect class or angle. Models linking surface processes with microclimate can be used to directly generate estimates of carbon, or used to down-scale soil survey-based estimates.

Scaling of Directed Dynamical Small-World Networks with Random Responses

NASA Astrophysics Data System (ADS)

Zhu, Chen-Ping; Xiong, Shi-Jie; Tian, Ying-Jie; Li, Nan; Jiang, Ke-Sheng

2004-05-01

A dynamical model of small-world networks, with directed links which describe various correlations in social and natural phenomena, is presented. Random responses of sites to the input message are introduced to simulate real systems. The interplay of these ingredients results in the collective dynamical evolution of a spinlike variable S(t) of the whole network. The global average spreading length s and average spreading time s are found to scale as p-αln(N with different exponents. Meanwhile, S(t) behaves in a duple scaling form for N≫N*: S˜f(p-βqγt˜), where p and q are rewiring and external parameters, α, β, and γ are scaling exponents, and f(t˜) is a universal function. Possible applications of the model are discussed.

Quantifying the effects of mountain pine beetle infestation on water and biogeochemical cycles at multiple spatial and temporal scales

NASA Astrophysics Data System (ADS)

Brooks, P. D.; Harpold, A. A.; Somor, A. J.; Troch, P. A.; Gochis, D. J.; Ewers, B. E.; Pendall, E.; Biederman, J. A.; Reed, D.; Barnard, H. R.; Whitehouse, F.; Aston, T.; Borkhuu, B.

2010-12-01

Unprecedented levels of bark beetle infestation over the last decade have radically altered forest structure across millions of hectares of Western U.S. montane environments. The widespread extent of this disturbance presents a major challenge for governments and resource managers who lack a predictive understanding of how water and biogeochemical cycles will respond to this disturbance over various temporal and spatial scales. There is a widespread perception, largely based on hydrological responses to fire or logging, that a reduction in both transpiration and interception following tree death will increase soil water availability and catchment water yield. However, few studies have directly addressed the effects of insect-induced forest decline on water and biogeochemical cycling. We address this knowledge gap using observations and modeling at scales from 100 to 109 m2 across study sites in CO and WY that vary in the intensity and timing of beetle infestation and tree death. Our focus on multiple sites with different levels of impact allows us to address two broad, organizing questions: How do changes in vegetation structure associated with MPB alter the partitioning of energy and water? And How do these changes in energy and water availability affect local to regional scale water and biogeochemical cycles? This presentation will focus primarily on energy balance and water partitioning, providing context for ongoing biogeochemical work. During the growing season, stand-scale transpiration declines rapidly and soil moisture increases following infestation, consistent with streamflow data from regional catchments that shows an increase in baseflow following widespread attack. During the winter and spring, stand scale snow surveys and continuous snow depth sensors suggested that the variability in snow cover decreased as the severity of beetle impact increases, but there were no significant stand-scale differences in snow depth among levels of impact. This is due both to an increase in snow under the canopies of dead trees and a decrease in snow cover in canopy gaps. For example, mean snow depth under the canopy was 86cm (CV 0.02) in unimpacted sites and 95cm (CV 0.05) in heavily impacted sites. In canopy gaps however, mean snow depth was 117cm (CV 0.11) in unimpacted sites but only 93cm (CV 0.07) in heavily impacted sites. At the watershed scale, bark beetle infestation was more likely to decrease the amount of both snowmelt and annual runoff, suggesting that the opening of the canopy increases sublimation and evaporation of the snow cover. These data suggest that the disturbance due to bark beetle infestation is both quantitatively and qualitatively different than either fire or logging. Using these observations, we develop a conceptual model for evaluating how biotic and abiotic processes couple water and biogeochemical cycles in forest ecosystems.