A Simple Computer Program for the Determination of Aquifer Characteristics from Pump Test Data     

Joseph C. Holzschuh III 《Ground water》1976,14(5):283-285

  相似文献   

Connection of the stratospheric QBO with global atmospheric general circulation and tropical SST. Part II: interdecadal variations     

Zeng-Zhen Hu  Bohua Huang  James L. Kinter III  Zhaohua Wu  Arun Kumar 《Climate Dynamics》2012,38(1-2):25-43

The interdecadal variation of the association of the stratospheric quasi-biennial oscillation (QBO) with tropical sea surface temperature (SST) anomalies (SSTA) and with the general circulation in the troposphere and lower stratosphere is examined using the ERA40 and NCEP/NCAR reanalyses, as well as other observation-based analyses. It is found that the relationship between the QBO and tropical SSTA changed once around 1978–1980, and again in 1993–1995. During 1966–1974, negative correlation between the QBO and NINO3.4 indices reached its maximum when the NINO3.4 index lagged the QBO by less than 6?months. Correspondingly, the positive correlations were observed when the NINO3.4 index led the QBO by about 11–13?months or lagged by about 12–18?months. However, maximum negative correlations were shifted from the NINO3.4 index lagging the QBO by about 0–6?months during 1966–1974 to about 3–12?months during 1985–1992. During 1975–1979, both the negative and positive correlations were relatively small and the QBO and ENSO were practically unrelated to each other. The phase-based QBO life cycle composites also confirm that, on average, there are two phase (6–7?months) delay in the evolution of the QBO-associated anomalous Walker circulation, tropical SST, atmospheric stability, and troposphere and lower stratosphere temperature anomalies during 1980–1994 in comparison with those in 1957–1978. The interdecadal variation of the association between the QBO and the troposphere variability may be largely due to the characteristic change of El Ni?o-Southern Oscillation. The irregularity of the QBO may play a secondary role in the interdecadal variation of the association.  相似文献   

Current status of ENSO prediction skill in coupled ocean–atmosphere models     

Emilia K. Jin  James L. Kinter III  B. Wang  C.-K. Park  I.-S. Kang  B. P. Kirtman  J.-S. Kug  A. Kumar  J.-J. Luo  J. Schemm  J. Shukla  T. Yamagata 《Climate Dynamics》2008,31(6):647-664

The overall skill of ENSO prediction in retrospective forecasts made with ten different coupled GCMs is investigated. The coupled GCM datasets of the APCC/CliPAS and DEMETER projects are used for four seasons in the common 22 years from 1980 to 2001. As a baseline, a dynamic-statistical SST forecast and persistence are compared. Our study focuses on the tropical Pacific SST, especially by analyzing the NINO34 index. In coupled models, the accuracy of the simulated variability is related to the accuracy of the simulated mean state. Almost all models have problems in simulating the mean and mean annual cycle of SST, in spite of the positive influence of realistic initial conditions. As a result, the simulation of the interannual SST variability is also far from perfect in most coupled models. With increasing lead time, this discrepancy gets worse. As one measure of forecast skill, the tier-1 multi-model ensemble (MME) forecasts of NINO3.4 SST have an anomaly correlation coefficient of 0.86 at the month 6. This is higher than that of any individual model as well as both forecasts based on persistence and those made with the dynamic-statistical model. The forecast skill of individual models and the MME depends strongly on season, ENSO phase, and ENSO intensity. A stronger El Niño is better predicted. The growth phases of both the warm and cold events are better predicted than the corresponding decaying phases. ENSO-neutral periods are far worse predicted than warm or cold events. The skill of forecasts that start in February or May drops faster than that of forecasts that start in August or November. This behavior, often termed the spring predictability barrier, is in part because predictions starting from February or May contain more events in the decaying phase of ENSO.  相似文献   

Dust formation and evolution in a Ca–Fe–SiO–H₂–O₂ vapour phase condensation experiment and astronomical implications     

Frans J. M. Rietmeijer  Aurora Pun  Joseph A. Nuth III 《Monthly notices of the Royal Astronomical Society》2009,396(1):402-408

Here, we report on a kinetically controlled vapour phase condensation experiment using a low-calcium Ca–Fe–SiO–H₂–O₂ vapour. Under these conditions of extreme disequilibrium, the condensate properties become predictable. They are amorphous solids with (predictable) deep metastable eutectic compositions. This study also shows how chemical evolution of the condensate grains will lead to chemically complex amorphous solids. The highly disordered structure of the deep metastable eutectic condensates is the very key to this predictable chemical evolution to grains with a silicate mineral composition, yet being amorphous. We compare our results with astronomical observations of dust around young stellar objects.  相似文献   

Equilibrium H/H fractionations in organic molecules: I. Experimental calibration of ab initio calculations     

Ying Wang  Alex L. Sessions  Robert J. Nielsen  William A. Goddard III 《Geochimica et cosmochimica acta》2009,73(23):7060-7075

Carbon-bound hydrogen in sedimentary organic matter can undergo exchange over geologic timescales, altering its isotopic composition. Studies investigating the natural abundance distribution of ¹H and ²H in such molecules must account for this exchange, which in turn requires quantitative knowledge regarding the endpoint of exchange, i.e., the equilibrium isotopic fractionation factor (α_eq). To date, relevant data have been lacking for molecules larger than methane. Here we describe an experimental method to measure α_eq for C-bound H positions adjacent to carbonyl group (H_α) in ketones. H at these positions equilibrates on a timescale of days as a result of keto-enol tautomerism, allowing equilibrium ²H/¹H distributions to be indirectly measured. Molecular vibrations for the same ketone molecules are then computed using Density Functional Theory at the B3LYP/6-311G** level and used to calculate α_eq values for H_α. Comparison of experimental and computational results for six different straight and branched ketones yields a temperature-dependent linear calibration curve with slope = 1.081−0.00376T and intercept = 8.404−0.387T, where T is temperature in degrees Celsius. Since the dominant systematic error in the calculation (omission of anharmonicity) is of the same size for ketones and C-bound H in most other linear compounds, we propose that this calibration can be applied to analogous calculations for a wide variety of organic molecules with linear carbon skeletons for temperatures below 100 °C. In a companion paper (Wang et al., 2009) we use this new calibration dataset to calculate the temperature-dependent equilibrium isotopic fractionation factors for a range of linear hydrocarbons, alcohols, ethers, ketones, esters and acids.  相似文献   

Global-scale near infrared variability on Mars: Analysis of 2003 Mars opposition observations from HST/NICMOS     

E. Noe Dobrea  J.F. Bell III  K. Noll  C.C. Million 《Icarus》2008,193(1):112-124

We have used HST/NICMOS to observe approximately 57% of the martian surface in 7 narrow band filters (0.97, 1.08, 1.13, 1.66, 1.90, 2.12, and 2.15 μm) during the 2003 opposition (Ls∼250°) and at a resolution of ∼12 km/pixel. Principal components analysis (PCA) of the dataset has identified regional variability on scales of hundreds of kilometers associated with differences in the near-infrared spectrum of Mars. Visualization of the data in principal component space has allowed us to identify spectral endmembers associated with the south polar cap, the classic bright terrains, northern Syrtis Major, southern Syrtis Major, Tyrrhena Terra, and Acidalia Planitia. The two Syrtis Major endmembers and the Tyrrhena Terra endmember differ in their absolute reflectivities but have the same spectral shape at wavelengths longer than 1.6 μm. The Acidalia endmember is distinct from the other dark terrain endmembers because it exhibits a strong negative near-IR spectral slope. Comparisons with spectral library measurements cannot provide unique constraints on the surface mineralogy for these sparsely-sampled spectral data. However, the observed spectral variations between Tyrrhena Terra and Syrtis Major are consistent with variations in iron- and sulfur-bearing minerals, and the relatively strong negative spectral slope in the spectrum of Acidalia is consistent with the presence of hydrated alteration products. Additional comparison with previous NICMOS observations taken in 1997 at Ls∼150° indicate that the average near-IR spectral slope of the Acidalia region is more negative during the late northern fall than during the mid northern summer. This may indicate seasonal variations in the presence of either adsorbed water or re-hydrated minerals in the regolith of Acidalia.  相似文献   

Climate, weather, and north polar observations from the Mars Reconnaissance Orbiter Mars Color Imager     

Michael C. Malin  Bruce A. Cantor  Robert M. Haberle  Peter C. Thomas  James F. Bell III 《Icarus》2008,194(2):501-512

The Mars Reconnaissance Orbiter observes Mars from a nearly circular, polar orbit. From this vantage point, the Mars Color Imager extends the ∼5 Mars years record of Mars Global Surveyor global, visible-wavelength multi-color observations of meteorological events and adds measurements at three additional visible and two ultraviolet wavelengths. Observations of the global distribution of ozone (which anti-correlates with water vapor) and water ice and dust clouds allow tracking of atmospheric circulation. Regional and local observations emphasize smaller scale atmospheric dynamics, especially those related to dust lifting and subsequent motion. Polar observations detail variations related to the polar heat budget, including changes in polar frosts and ices, and storms generated at high thermal contrast boundaries.  相似文献   

Spatial and Temporal Patterns Associated with Permitted Tree Removal in Austin,Texas, 2002–2011     

Brendan L. Lavy  Ronald R. Hagelman III 《The Professional geographer》2017,69(4):539-552

A wide-ranging set of physical, urban, demographic, socioeconomic, and policy characteristics determines the spatial distribution of urban forests. Information on the characteristics surrounding tree removals on both public and private properties has received less attention in the literature. The purpose of this research was to analyze the spatiotemporal trends and geographic patterns of tree removals in Austin, Texas, between 2002 and 2011 in an effort to understand how site-specific characteristics influence urban tree removal and affect the overall distribution of Austin's urban forest. We examined permitted tree removals using a geographic information system (GIS) as well as spatial and statistical analyses. Specifically, we evaluated the degree to which variables related to various physical, urban, and socioeconomic conditions predicted tree removals. The results indicate that permitted tree removals and their associated characteristics in Austin have varied over the ten-year study period. Permitted tree removals increased over the study period and took place in the urban core and along the urban periphery. Permitted tree removals were more likely to be undertaken by college graduates and owner-occupants and to occur in more densely populated areas, closer to major streets, and on properties with older structures. The results of this research provide urban forest professionals with information on the location and intensity of permitted tree removals and the significant characteristics driving urban tree loss.  相似文献   

Integrating Stalagmite, Vertebrate, and Pollen Sequences to Investigate Holocene Vegetation and Climate Change in the Southern Midwestern United States     

Rhawn F. Denniston  Luis A. Gonzalez  Holmes A. Semken  Jr.  Yemane Asmerom  Richard G. Baker  Heather Recelli-Snyder  Mark K. Reagan  E. Arthur Bettis  III 《Quaternary Research》1999,52(3):381

Speleothem carbon and oxygen isotopic records from Onondaga Cave, south-central Missouri, and Beckham Creek Cave, north-central Arkansas, are compared with the Cupola Pond and Oldfield Swamp pollen series from southeastern Missouri and the Rodgers Shelter and Modoc Shelter vertebrate biostratigraphic sequences from central Missouri and southwestern Illinois. Similar, and roughly contemporaneous, shifts between deciduous forest and steppe indicators throughout the Holocene are revealed in each database. These independent proxies record steppe conditions between approximately 9000 and 1500 cal yr B.P. A shift toward lighter speleothem carbon may reflect a change from warm and dry to cool and dry conditions between 4500 and 3000 yr B.P. The sensitive response of speleothem δ¹³C to changes in vegetation emphasizes their importance as paleoclimate records in an area containing few other millenial-scale climate proxies.  相似文献   

The Development of Groundwater Modeling: The End of an Era          下载免费PDF全文

Fred J. Molz III 《Ground water》2017,55(1):1-1

  相似文献