Satellite Estimates and Shipboard Observations of Downward Radiative Fluxes at the Ocean Surface

2008 ◽  
Vol 25 (3) ◽  
pp. 429-441 ◽  
Author(s):  
G. Guo ◽  
J. A. Coakley
Keyword(s):  
Radiant Energy ◽  
Absolute Magnitude ◽  
Weather Data ◽  
Radiative Fluxes ◽  
Oregon Coast ◽  
The Mean ◽  
The Absolute ◽  
Mean Differences ◽  
The Times ◽  
Longwave Flux

Abstract Clouds and the Earth’s Radiant Energy System (CERES) uses a suite of instruments on the Terra and Aqua satellites combined with analyzed weather data and information on surface conditions to estimate surface radiative fluxes. CERES estimates for the Terra satellite were compared with measurements of the surface radiative fluxes collected with the research vessels (RVs) Wecoma and Thomas G. Thompson radiometers for cruises off the Oregon coast undertaken during 2000–03. To assess the shipboard measurements, the radiometer observations were analyzed to identify cloud-free conditions characterized by ∼1–2 h of relatively stable radiative fluxes. Fluxes for the cloud-free conditions were compared with those calculated using profiles of temperature and humidity from analyzed meteorological fields for the times and locations of the measurements and broadband radiative transfer models. For summertime conditions along the Oregon coast, and assuming a marine aerosol having 0.55-μm optical depth of 0.05, modeled and observed values of the shortwave flux agreed to within 1%–2%. Similar comparisons for the downward cloud-free longwave flux were within 1%–3%. This agreement also held for the CERES surface radiative flux estimates with CERES cloud-free fields of view for ocean scenes within 50 km of the ship being compared with 30-min averages of the shipboard measurements centered on the times of the Terra overpass. Using the CERES observations to identify cloud-free conditions for the Wecoma revealed that in some cases the shipboard measurements of the shortwave flux varied erratically. Criteria were adopted to avoid such behavior, yielding periods in which the surface radiative fluxes were reasonably stable for a range of cloud-free and cloudy conditions. With the criteria applied, the absolute magnitude of the mean differences between the shipboard measurements and the CERES estimates for the downward shortwave flux were within 2%, with RMS differences less than 6% within each month of CERES–shipboard matchups. The absolute magnitude of the mean differences for the downward longwave flux was less than 2%, with RMS differences less than 5%.

scholarly journals The Luminosity Determination

1995 ◽  
Vol 10 ◽  
pp. 399-402
Author(s):  
A.E. Gómez ◽  
C. Turon
Keyword(s):  
Main Sequence ◽  
Small Volume ◽  
Absolute Magnitude ◽  
Fitting Procedure ◽  
Trigonometric Parallaxes ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes ◽  
Kinematical Data ◽  
Magnitude Determination

The Hertzprung-Russel (HR) diagram luminosity calibration relies basically on three kinds of data: trigonometric parallaxes, kinematical data (proper motions and radial velocities) and cluster distances obtained by the zero-age main sequence fitting procedure. The most fundamental method to calculate the absolute magnitude is the use of trigonometric parallaxes, but up to now, accurate data only exist for stars contained in a small volume around the sun. Individual absolute magnitudes are obtained using trigonometric parallaxes or photometric and spectroscopic calibrations. In these calibrations the accuracy on the absolute magnitude determination ranges from ±0.m2 in the main sequence to ±0m5 in the giant branch. On the other hand, trigonometric parallaxes, kinematical data or cluster distances have been used to make statistical calibrations of the absolute magnitude. The standard error on the mean absolute magnitude calibrations ranges from ±0m3 to ±0m6 on the mean sequence, from ±0m5 to ±0m7 on thegiant branch and is of about 1mfor supergiants.Future improvements in the absolute magnitude determination will depend on the improvement of the basic data from the ground and space. A brief overview of the new available data is presented. In particular, the analysis of the first 30 months data of the Hipparcos mission (H30) (from the 37 months data of the whole mission) allows to perform a statistical evaluation of the improvements expected in the luminosity determination.

scholarly journals The Parallaxes of U Gem Variables

1979 ◽  
Vol 53 ◽  
pp. 494-494
Author(s):  
Karl W. Kamper
Keyword(s):  
Confidence Level ◽  
Absolute Magnitude ◽  
Weighted Mean ◽  
Quiescent Phase ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

An Allegheny parallax series of SS Cyg, consisting of 52 exposures obtained on 15 nights, was recently measured on the PDS microphotometer at the David Dunlap Observatory, and a value of (m.e.) derived for the absolute parallax. This is close to the mean of the two previous discordant measures for this star given in the table below. The weighted mean of the three determinations implies that the absolute magnitude, at quiescent phase, of the star is between 7.0 and 9.0 formally at a 90% confidence level. Recent parallax determinations made at Lick by Vasilevskls et al. (1975) for three other stars, listed below along with the Mt. Wilson value for U Gem, imply even fainter absolute magnitudes.

Observational selection and statistics of asteroids

1974 ◽  
Vol 22 ◽  
pp. 35-38
Author(s):  
T. Kiang
Keyword(s):  
Elementary Theory ◽  
Absolute Magnitude ◽  
Probabilistic Interpretation ◽  
Keplerian Motion ◽  
Observational Selection ◽  
Statistical Studies ◽  
The Mean ◽  
The Absolute ◽  
Osculating Elements ◽  
Elliptical Motion

In statistical studies of asteroids we usually deal with the osculating elementsa, e, π, i, Ω, and either the mean opposition magnitudem0or the absolute magnitudeg. We deliberately overlook the remaining osculating element, the mean anomaly at epoch, because we are not normally interested in the relatively fast changes in the complexion of the system brought about by the Keplerian motion; rather, we are concerned with the average complexion where each asteroid is replaced by a ring with aline densityρinversely proportional to the orbital speed. As is well known, Gauss used such rings to calculate secular inequalities, but here we give them a probabilistic interpretation:ρ. dλ is to be taken as the probability that an asteroid with given values of the elements is found in some particular range dλ of heliocentric longitude. We therefore putwhere dMis the interval in the mean anomaly corresponding to dλ. The function ρ is known from elementary theory of elliptical motion, but is rather complicated to write out explicitly.

scholarly journals Absolute Magnitude Calibration for Dwarfs Based on the Colour–Magnitude Diagrams of Galactic Clusters

2014 ◽  
Vol 31 ◽  
Author(s):  
S. Karaali ◽  
E. Yaz Gökçe ◽  
S. Bilir ◽  
S. Tunçel Güçtekin
Keyword(s):  
Standard Deviation ◽  
Absolute Magnitude ◽  
Derived Relations ◽  
Two Systems ◽  
Galactic Clusters ◽  
Solar Metallicity ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

AbstractWe present two absolute magnitude calibrations for dwarfs based on colour–magnitude diagrams of Galactic clusters. The combination of the Mg absolute magnitudes of the dwarf fiducial sequences of the clusters M92, M13, M5, NGC 2420, M67, and NGC 6791 with the corresponding metallicities provides absolute magnitude calibration for a given (g − r)0 colour. The calibration is defined in the colour interval 0.25 ≤ (g − r)0 ≤ 1.25 mag and it covers the metallicity interval − 2.15 ≤ [Fe/H] ≤ +0.37 dex. The absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the interval − 0.15 ≤ ΔMg ≤ +0.12 mag. The mean and standard deviation of the residuals are < ΔMg > = − 0.002 and σ = 0.065 mag, respectively. The calibration of the MJ absolute magnitude in terms of metallicity is carried out by using the fiducial sequences of the clusters M92, M13, 47 Tuc, NGC 2158, and NGC 6791. It is defined in the colour interval 0.90 ≤ (V − J)0 ≤ 1.75 mag and it covers the same metallicity interval of the Mg calibration. The absolute magnitude residuals obtained by the application of the procedure to the cluster M5 ([Fe/H] = −1.40 dex) and 46 solar metallicity, − 0.45 ≤ [Fe/H] ≤ +0.35 dex, field stars lie in the interval − 0.29 and + 0.35 mag. However, the range of 87% of them is rather shorter, − 0.20 ≤ ΔMJ ≤ +0.20 mag. The mean and standard deviation of all residuals are < ΔMJ > =0.05 and σ = 0.13 mag, respectively. The derived relations are applicable to stars older than 4 Gyr for the Mg calibration, and older than 2 Gyr for the MJ calibration. The cited limits are the ages of the youngest calibration clusters in the two systems.

scholarly journals A New Procedure for the Photometric Parallax Estimation

2003 ◽  
Vol 20 (3) ◽  
pp. 270-278 ◽  
Author(s):  
S. Karaali ◽  
Y. Karataş ◽  
S. Bilir ◽  
S. G. Ak ◽  
E. Hamzaoğlu
Keyword(s):  
Main Sequence ◽  
Large Range ◽  
Absolute Magnitude ◽  
Colour Index ◽  
Ultraviolet Excess ◽  
Magnitude Diagram ◽  
Single Colour ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

AbstractWe present a new procedure for photometric parallax estimation. The data for 1236 stars provide calibrations between the absolute magnitude offset from the Hyades main-sequence and the ultraviolet-excess for eight different (B–V)0 colour-index intervals, (0.3 0.4), (0.4 0.5), (0.5 0.6), (0.6 0.7), (0.7 0.8), (0.8 0.9), (0.9 1.0) and (1.0 1.1). The mean difference between the original and estimated absolute magnitudes and the corresponding standard deviation are rather small, +0.0002 and ±0.0613 mag. The procedure has been adapted to the Sloan photometry by means of colour equations and applied to a set of artificial stars with different metallicities. The comparison of the absolute magnitudes estimated by the new procedure and the canonical one indicates that a single colour–magnitude diagram does not supply reliable absolute magnitudes for stars with large range of metallicity.

scholarly journals 12. Satellite orbits and atmospheric densities at altitudes up to 750 kilometers obtained from the vanguard orbit determination program

1960 ◽  
Vol 10 ◽  
pp. 720-720
Author(s):  
Joseph W. Siry
Keyword(s):  
Orbit Determination ◽  
Satellite Orbits ◽  
Radio Observations ◽  
Mean Motion ◽  
The Mean ◽  
The Absolute ◽  
The Times ◽  
The Individual ◽  
Very High ◽  
The Way

The satellites 1958 β2 (Vanguard I) and 1958 γ (Explorer III) represent extremes from the orbit-determination standpoint. The absolute fluctuations in the mean motion were smallest for the former, and largest for the latter, among the satellites for which precision Minitrack radio observations were available. Accordingly, the orbit of the former has been determined with the greater precision. Even in the case of 1958 γ, however, the rootmean- square value of the residuals is less than twenty minutes of arc. The radial distances between adjacent arcs at the times for transferring from one arc to the next are of the same order as the residuals within the individual arcs. The results obtained with this satellite are of interest since they indicate what can be done in the way of determining the orbits of satellites having very low perigees and very high fineness ratios. Errors of less than four minutes of arc have been obtained for some of the orbital arcs of 1958 β2[1].

scholarly journals IV. A determination of the electromotive force of the weston normal cell in semi-absolute volts

1914 ◽  
Vol 214 (509-522) ◽  
pp. 147-198 ◽  
Keyword(s):  
Electromotive Force ◽  
Order Of Accuracy ◽  
Absolute Determination ◽  
A Value ◽  
Great Progress ◽  
The Mean ◽  
The Absolute ◽  
The Times ◽  
Made In

The measurement of the E. M. F. of the Weston cell affords the best means of comparing the performances of different methods and instruments for the absolute determination of the ampere. Great progress has been made in the last six years, but the most recent determinations by independent methods, giving equal promise of accuracy, still show discrepancies covering a range of 2 parts in 10,000, which must be debited for the most part to the difficulty of the absolute determination of current. Each method in itself appears to give an order of accuracy of repetition approaching, or even exceeding, 1 in 100,000. It is therefore of special interest and importance to compare the results of methods differing as widely as possible in experimental details in endeavouring to arrive at a value comparatively free from the constant errors which may beset any particular type of method. The measurements described by Mr. Shaw in the following paper were made by the method of the Weber bifilar electrodynamometer, as modified by Clerk Maxwell and Latimer Clark, which has not hitherto been employed for work of the highest accuracy, and which merits attention on account of its many fundamental points of difference from recent methods. The instrument originally supplied to McGill College for this purpose was a faithful copy of Clerk Maxwell’s instrument at Cambridge, of which the theory is given together with a figure and description in his ‘ Electricity and Magnetism,’ vol, 2, p. 367. The chief sources of error in this instru­ment were (1) the uncertainty of insulation of the coils, which proved to be of the order of nearly one half of 1 per cent.; (2) the difficulty of determining the mean radii of the coils, which were wound with silk-covered wire; (3) the want of rigidity of the pulley arrangement for equalising the tensions of the suspending wires, and the imperfect elasticity of the control, which depended too much on torsion, and made it impossible to obtain readings consistent to 1 in 1000 for the deflections or the times of oscillation. These defects were so fatal to accurate work even of the order of 1 in 10,000, which was all that it was originally contemplated, that it was found necessary to reconstruct the instrument entirely until nothing remained of the original except the frame, and even that required stiffening to a material extent.

scholarly journals Absolute-Magnitude Calibration for Red Giants Based on Colour–Magnitude Diagrams of Galactic Clusters: I. Calibration in V and B–V

2012 ◽  
Vol 29 (4) ◽  
pp. 509-522 ◽  
Author(s):  
S. Karaali ◽  
S. Bilir ◽  
E. Yaz Gökçe
Keyword(s):  
Standard Deviation ◽  
Magnitude Estimation ◽  
Absolute Magnitude ◽  
Red Giants ◽  
Degree Polynomial ◽  
Derived Relations ◽  
Galactic Clusters ◽  
The Mean ◽  
The Absolute ◽  
Effect Of Age

AbstractWe present an absolute-magnitude calibration for red giants using the colour–magnitude diagrams of six Galactic clusters with different metallicities: M92, M13, M5, 47 Tuc, M67 and NGC 6791. The combination of the absolute magnitude offset from the fiducial of giant sequence of the cluster M5 with the corresponding metallicity offset provides a calibration estimation for the absolute magnitude of red giants for a given (B – V)0 colour. The calibration is defined in the colour interval 0.75 ≤ (B – V)0 ≤ 1.50 mag and it covers the metal licity interval −2.15 > [Fe/H]≤+0.37 dex. 91% of the absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the interval −0.40 < ΔM≤+0.40 mag. The mean and the standard deviation of the residuals are 0.05 and 0.19 mag, respectively. We fitted the absolute magnitude also to metallicity and age for a limited sub-sample of (B – V)0 colour, just to test the effect of age in absolute-magnitude calibration. Comparison of the mean and the standard deviation of the residuals evaluated by this procedure with the corresponding ones provided by the procedure where the absolute magnitude fitted to a third degree polynomial of metallicity show that the age parameter may be omitted in absolute magnitude estimation of red giants. The derived relations are applicable to stars older than 4 Gyr, the age of the youngest calibrating cluster.

Anatomical accuracy of lesion localization

2005 ◽  
Vol 44 (04) ◽  
pp. 149-155 ◽  
Author(s):  
W. Römer ◽  
T. Hothorn ◽  
A. Pfahlberg ◽  
J. Hornegger ◽  
W. Bautz ◽  
...  
Keyword(s):  
Rigid Body ◽  
Positron Emission ◽  
Oncological Patients ◽  
Bowel Movements ◽  
Malignant Lesions ◽  
The Mean ◽  
The Absolute ◽  
Ct Data ◽  
Mean Differences ◽  
Lesion Localization

SummaryThe aim of this study was to evaluate the anatomical accuracy and reproducibility of retrospective interactive rigid image registration (RIR) between routinely archived X-ray computer tomography (CT) and positron emission tomography performed with 18F-deoxyglucose (FDG-PET) in oncological patients. Methods: Two observers registered PET and CT data obtained in 37 patients using a commercially available image fusion tool. RIR was performed separately for the thorax and the abdomen using physiological FDG uptake in several organs as a reference. One observer performed the procedure twice (O1a and O1b), another person once (O2). For 94 malignant lesions, clearly visible in CT and PET, the signed and absolute distances between their representation on PET and CT were measured in X-, Y-, and Z-direction with reference to a coordinate system centered in the CT representation of each lesion (X-, Y-, Z-distances). Results: The mean differences of the signed and absolute distances between O1a, O1b, and O2 did not exceed 3 mm in any dimension. The absolute X-, Y-, and Z-distances ranged between 0.57 ± 0.58 cm for O1a (X-direction) and 1.12 ± 1.28 cm for O2 (Z-direction). When averaging the absolute distances measured by O1a, O1b, and O2, the percentage of lesions misregistered by less than 1.5 cm was 91 % for the X-, 88 % for the Y-, and 77 % for the Z-direction. The larger error of fusion determined for the remaining lesions was caused by non-rigid body transformations due to differences in breathing, arm position, or bowel movements between the two examinations. Mixed effects analysis of the signed and absolute X-, Y-, and Z-distances disclosed a significantly greater misalignment in the thorax than in the abdomen as well as axially than transaxially. Conclusion: The anatomical inaccuracy of RIR can be expected to be <1.5 cm for the majority of neoplastic foci. Errors of alignment are bigger in the thorax and in Z-direction, due to non-rigid body transformations caused, e.g., by breathing.

CANADIAN WILTSHIRE BACON: VIII. COLOUR OF BACON AND ITS CORRELATION WITH CHEMICAL ANALYSES

1940 ◽  
Vol 18d (6) ◽  
pp. 217-224 ◽  
Author(s):  
C. A. Winkler ◽  
J. W. Hopkins ◽  
M. W. Thistle
Keyword(s):  
Absolute Magnitude ◽  
Moderate Degree ◽  
The Mean ◽  
Mean Differences ◽  
Photoelectric Measurements ◽  
Degree Of Association ◽  
Range Of Variation ◽  
Blue Intensity ◽  
Nitrite Content

Photoelectric measurements on two factory-cured Wiltshire sides from each of 22 Canadian packing plants, sampled (i) upon receipt at the laboratory, (ii) after storage for 10 days at 1 °C., and (iii) after smoking for 14 hr. at 40 °C., indicated statistically significant differences between individual sides in respect of both total intensity and quality of colour, which would seem to have arisen mainly from differences between plants. The average range of variation between plants was: total intensity, 25%; red intensity, 23%; green, 30%; and blue, 35% of the mean. Differences in colour quality of two types, (i) due to variations in the component intensities which were correlated but not of the same absolute magnitude, and (ii) due to uncorrected variation in the component intensities, were demonstrable.Partial correlation studies led to the deduction of a moderate degree of association between colour quality, and pH and nitrite content, under the conditions of sampling (ii). Increased acidity was accompanied by an enhanced green and a depressed blue intensity. Increased nitrite content also tended to depress blue intensity, but apparently without significantly affecting the green. No correlation between colour and the salt, nitrate or moisture content of the meat was demonstrable.

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