To: “An exact solution for the gravity curvature (Bullard B) correction” by T. R. LaFehr (GEOPHYSICS, 56, 1179–1184, August 1991)

Geophysics ◽  
1992 ◽  
Vol 57 (2) ◽  
pp. 370-370 ◽  
Keyword(s):  
Exact Solution ◽  
Sea Level ◽  
Difference Graph ◽  
The Difference

In Figure 2 on p. 1180, the difference graph should show a scale of microgal per decameters or microgal per 10 m; near sea level, the correction is about 1.4 microgal per m, not 14 microgal per m.

Changes of Ionic and Oxygen Isotopic Composition of the Snowpack at the Glacier Austre Okstindbreen, Norway, 1995

1998 ◽  
Vol 29 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Peter Raben ◽  
Wilfred H. Theakstone
Keyword(s):  
Isotopic Composition ◽  
Sea Level ◽  
Oxygen Isotopes ◽  
Oxygen Isotopic Composition ◽  
Isotopic Ratios ◽  
Vertical Variations ◽  
Oxygen Isotopic ◽  
The Difference ◽  
Liquid Precipitation ◽  
Different Altitudes

Marked vertical variations of ions and oxygen isotopes were present in the snowpack at the glacier Austre Okstindbreen during the pre-melting phase in 1995 at sites between 825 m and 1,470 m above sea level. As the first meltwater percolated from the top of the pack, ions were moved to a greater depth, but the isotopic composition remained relatively unchanged. Ions continued to move downwards through the pack during the melting phase, even when there was little surface melting and no addition of liquid precipitation. The at-a-depth correlation between ionic concentrations and isotopic ratios, strong in the pre-melting phase, weakened during melting. In August, concentrations of Na+ and Mg2+ ions in the residual pack were low and vertical variations were slight; 18O enrichment had occurred. The difference of the time at which melting of the snowpack starts at different altitudes influences the input of ions and isotopes to the underlying glacier.

On the convergence of difference schemes for the generalized BBM–Burgers equation

2019 ◽  
Vol 26 (3) ◽  
pp. 341-349 ◽  
Author(s):  
Givi Berikelashvili ◽  
Manana Mirianashvili
Keyword(s):  
Exact Solution ◽  
Sobolev Space ◽  
Difference Scheme ◽  
Absolute Stability ◽  
Burgers Equation ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Algebraic Equations ◽  
The Difference ◽  
Initial Boundary Value

Abstract A three-level finite difference scheme is studied for the initial-boundary value problem of the generalized Benjamin–Bona–Mahony–Burgers equation. The obtained algebraic equations are linear with respect to the values of the desired function for each new level. The unique solvability and absolute stability of the difference scheme are shown. It is proved that the scheme is convergent with the rate of order {k-1} when the exact solution belongs to the Sobolev space {W_{2}^{k}(Q)} , {1<k\leq 3} .

Cerebrospinal fluid in man native to high altitude

1964 ◽  
Vol 19 (2) ◽  
pp. 319-321 ◽  
Author(s):  
J. W. Severinghaus ◽  
A. Carceleń B.
Keyword(s):  
Cerebrospinal Fluid ◽  
High Altitude ◽  
Sea Level ◽  
Regulation Of Respiration ◽  
Acid Base ◽  
Peripheral Chemoreceptor ◽  
Arterial Blood ◽  
Blood Ph ◽  
The Difference

CSF pH was shown in a prior report to remain essentially constant during 8 days of acclimatization to 3,800 m. In order to further evaluate the possible role of CSF acid-base equilibria in the regulation of respiration, 20 Peruvian Andean natives were studied at altitudes of 3,720–4,820 m. In ten subjects at 3,720 m, means were: CSF pH 7.327, Pco2 43, HCO3- 21.5, Na+ 136, K+ 2.6, Cl- 124, lactate 30 mg/100 ml. Arterial blood: pH 7.43, Pco2 32.5, HCO3- 21.3, Na+ 136, K+ 4.2, Cl- 107, hematocrit 49, SaOO2 89.6. In six subjects at 4,545 m and four at 4,820 m CSF values were not significantly different; mean arterial Pco2 was 32.6 and 32.3, respectively. The only significant variations with altitude were the expected lowering of PaOO2 to 47 and 43.5 mm Hg, and of SaOO2 to 84.2 and 80.7, and increase of hematocrit to 67% and 75%, respectively. The natives differed from recently acclimatized sea-level residents in showing less ventilation (higher Pco2) in response to the existing hypoxia, and less alkaline arterial blood. The difference appears to relate to peripheral chemoreceptor response to hypoxia rather than central medullary chemoreceptor. respiratory regulation at high altitude; chronic acclimatization to altitude; peripheral chemoreceptor response to hypoxia; CSF and medullary respiratory chemoreceptors Submitted on June 12, 1963

The new gravity system—changes in international gravity base values and anomaly values

Geophysics ◽  
1979 ◽  
Vol 44 (8) ◽  
pp. 1352-1366 ◽  
Author(s):  
George P. Woollard
Keyword(s):  
Sea Level ◽  
Global Scale ◽  
Absolute Gravity ◽  
Geodetic Reference System ◽  
Limiting Factor ◽  
Worldwide Distribution ◽  
The Difference ◽  
Correction Terms ◽  
Discernible Difference ◽  
Gravity System

An assessment is made of (1) the reliability of the changes in the absolute gravity datum and standard incorporated in the IGSN 71 values of Morelli et al (1974), and (2) the effect of these changes and those incorporated in the new international gravity formula (Geodetic Reference System 1967) defining theoretical gravity values at sea level on gravity anomaly values. Pendulum‐interval comparisons with modern absolute gravity intervals between Washington, D.C.; Teddington, England; Paris, France; and Potsdam, East Germany indicate that the correction of 14 mgal to the Potsdam datum is correct to within .03 ± .016 mgal. Although there appear to be occasional discrepancies in the IGSN 71 values of the order of 0.1 mgal, in general their reliability appears to approximate ±0.05 mgal. A discrepancy of approximately −0.03 mgal per 1000 mgal of absolute gravity is indicated, however, in the gravity standard defined by the IGSN 71 values over the range of modern absolute gravity determinations between Fairbanks, Alaska and Bogotá, Colombia. An evaluation of the earlier attempt to standardize gravity on a global scale (Woollard and Rose, 1963) indicates a mean datum difference of 14.7 mgal (standard deviation 0.2 mgal) relative to IGSN 71 values at 776 sites having a worldwide distribution. No discernible difference in gravity standard from that of the IGSN 71 values is indicated except in South America, where the Woollard and Rose values are found to incorporate a difference in standard of O.2 mgal per 1000 mgal. It is shown that anomaly conversions from the old to the new gravity system can be effected directly using the old anomaly values. Two correction terms are required, specifically, (1) a constant representing the difference in base value used relative to the IGSN 71 value for the base, and (2) a latitude‐dependent term representing the difference in theoretical sea level gravity using the old International Gravity Formula (IGF) and the new GRS 67 formula. Test conversions of anomaly values on the old gravity system for regional areas involving data from several sources indicate that, in general, anomaly conversion to the new gravity system can be obtained with a reliability of about 0.3 to 0.5 mgal. The limiting factor is the unknown variation in gravimeter calibration standards represented.

scholarly journals Strong and weak divergence in finite time of Euler's method for stochastic differential equations with non-globally Lipschitz continuous coefficients

2010 ◽  
Vol 467 (2130) ◽  
pp. 1563-1576 ◽  
Author(s):  
Martin Hutzenthaler ◽  
Arnulf Jentzen ◽  
Peter E. Kloeden
Keyword(s):  
Exact Solution ◽  
Finite Time ◽  
Weak Sense ◽  
Mean Square ◽  
Euler’S Method ◽  
Lipschitz Continuous ◽  
The Difference ◽  
And Diffusion ◽  
Weak Divergence ◽  
Time Point

The stochastic Euler scheme is known to converge to the exact solution of a stochastic differential equation (SDE) with globally Lipschitz continuous drift and diffusion coefficients. Recent results extend this convergence to coefficients that grow, at most, linearly. For superlinearly growing coefficients, finite-time convergence in the strong mean-square sense remains. In this article, we answer this question to the negative and prove, for a large class of SDEs with non-globally Lipschitz continuous coefficients, that Euler’s approximation converges neither in the strong mean-square sense nor in the numerically weak sense to the exact solution at a finite time point. Even worse, the difference of the exact solution and of the numerical approximation at a finite time point diverges to infinity in the strong mean-square sense and in the numerically weak sense.

scholarly journals Variations in the difference between mean sea level measured either side of Cape Hatteras and their relation to the North Atlantic Oscillation

2016 ◽  
Vol 49 (7-8) ◽  
pp. 2451-2469 ◽  
Author(s):  
P. L. Woodworth ◽  
M. Á. Morales Maqueda ◽  
W. R. Gehrels ◽  
V. M. Roussenov ◽  
R. G. Williams ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
Sea Level ◽  
North Atlantic ◽  
Mean Sea Level ◽  
The North ◽  
Cape Hatteras ◽  
The North Atlantic ◽  
The Difference ◽  
The North Atlantic Oscillation

Stokes flow past bubbles and drops partially coated with thin films. Part 1. Stagnant cap of surfactant film – exact solution

1983 ◽  
Vol 126 ◽  
pp. 237-250 ◽  
Author(s):  
S. S. Sadhal ◽  
Robert E. Johnson
Keyword(s):  
Exact Solution ◽  
Liquid Drop ◽  
Mixed Boundary ◽  
Mixed Boundary Conditions ◽  
Creeping Flow ◽  
Immiscible Fluid ◽  
Interfacial Tensions ◽  
Surfactant Film ◽  
Dual Series Equations ◽  
The Difference

In this investigation the creeping flow due to the motion of a liquid drop or a bubble in another immiscible fluid is examined when the interface is partially covered by a stagnant layer of surfactant. The associated boundary-value problem involves mixed boundary conditions at the interface, which lead to a set of dual series equations. An inversion of these equations yields the exact solution to the stagnant cap problem.Several useful results are obtained in closed form. Among these are the expressions for the drag force, the difference between the maximum and the minimum interfacial tensions, and the amount of adsorbed surfactant. A shifting of the centre of the internal vortex is observed.

scholarly journals Modeling the Impacts of Sea Level Rise on Storm Surge Inundation in Flood-Prone Urban Areas of Hampton Roads, Virginia

2018 ◽  
Vol 52 (2) ◽  
pp. 92-105 ◽  
Author(s):  
Luca Castrucci ◽  
Navid Tahvildari
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Hydrodynamic Model ◽  
Urban Areas ◽  
The United States ◽  
Hampton Roads ◽  
Level Data ◽  
The Difference ◽  
Surge Flooding

AbstractHampton Roads is a populated area in the United States Mid-Atlantic region that is highly affected by sea level rise (SLR). The transportation infrastructure in the region is increasingly disrupted by storm surge and even minor flooding events. The purpose of this study is to improve our understanding of SLR impacts on storm surge flooding in the region. We develop a hydrodynamic model to study the vulnerability of several critical flood-prone neighborhoods to storm surge flooding under several SLR projections. The hydrodynamic model is validated for tide prediction, and its performance in storm surge simulation is validated with the water level data from Hurricane Irene (2011). The developed model is then applied to three urban flooding hotspots located in Norfolk, Chesapeake, and the Isle of Wight. The extent, intensity, and duration of storm surge inundation under different SLR scenarios are estimated. Furthermore, the difference between the extent of flooding as predicted by the hydrodynamic model and the “bathtub” approach is highlighted.

Altitudinal variation in parental energy expenditure by white-crowned sparrows

2002 ◽  
Vol 205 (18) ◽  
pp. 2915-2924 ◽  
Author(s):  
Wesley W. Weathers ◽  
Charisse L. Davidson ◽  
Christopher R. Olson ◽  
Martin L. Morton ◽  
Nadav Nur ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Sea Level ◽  
Thermal Environment ◽  
Level Population ◽  
Interindividual Variation ◽  
Effect Of Temperature ◽  
Operative Temperature ◽  
Physiological Capacity ◽  
Higher Temperature ◽  
The Difference

SUMMARY We used the doubly labeled water technique to measure daily energy expenditure (DEE) during the incubation and feeding nestling stages in two populations of white-crowned sparrows (Zonotrichia leucophrys)— one montane and migratory, the other coastal and sedentary —that differ in thermal environment and clutch size. We assessed the birds'thermal environment by continuously monitoring (among other variables)operative temperature and wind speed both in the open and within bushes and willow thickets occupied by sparrows. From these measurements, we derived several estimates of the birds' thermal environment, including standard operative temperature (Tes). Shade air temperature and Tes averaged 6.6 and 10.3°C lower, respectively, at the montane study site during DEE measurements. The montane population's DEE averaged 24% higher than that of the sea-level population (103.6±12.2 versus 83.7±9.6 kJ day-1; means ± S.D., N=31 and 22, respectively), reflecting both its larger brood size(3.7 versus 2.9) and the colder environment. The DEE:BMR ratio was lowest in the sea-level population (2.1 versus 2.6), but neither population worked to their physiological capacity to produce young. DEE was significantly correlated with temperature across populations, with Tes explaining 42% of the variation in DEE. Statistically removing the effect of temperature by adjusting DEE to a common temperature reduced the difference in DEE between populations by 34% to 87.7 and 100.8 kJ day-1, respectively, for sea-level and montane populations. Basal and resting metabolic rates were similar in both populations, implying that greater activity in the montane population accounted for its higher temperature-adjusted DEE. Our results indicate that the thermal context within which behavior occurs can significantly affect interindividual variation in DEE. Attempts to assess reproductive effort by measuring DEE should therefore account explicitly for the effect of temperature.

Sign in / Sign up

Export Citation Format

Share Document