The solar chemical composition is an important ingredient in our understanding of the formation, structure, and evolution of both the Sun and our Solar System. Furthermore, it is an essential refer ...

The Chemical Composition of the Sun

https://ntrs.nasa.gov/api/citations/20090027884/downloads/20090027884.pdf

Summary of Current Radiometric Calibration Coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI Sensors

A large data set containing coincident in situ chlorophyll and remote sensing reflectance measurements was used to evaluate the accuracy, precision, and suitability of a wide variety of ocean color chlorophyll algorithms for use by SeaWiFS (Sea-viewing Wide Field-of-view Sensor). The radiance-chlorophyll data were assembled from various sources during the SeaWiFS Bio-optical Algorithm Mini-Workshop (SeaBAM) and is composed of 919 stations encompassing chlorophyll concentrations between 0.019 and 32.79 μg L−1. Most of the observations are from Case I nonpolar waters, and ∼20 observations are from more turbid coastal waters. A variety of statistical and graphical criteria were used to evaluate the performances of 2 semianalytic and 15 empirical chlorophyll/pigment algorithms subjected to the SeaBAM data. The empirical algorithms generally performed better than the semianalytic. Cubic polynomial formulations were generally superior to other kinds of equations. Empirical algorithms with increasing complexity (number of coefficients and wavebands), were calibrated to the SeaBAM data, and evaluated to illustrate the relative merits of different formulations. The ocean chlorophyll 2 algorithm (OC2), a modified cubic polynomial (MCP) function which uses Rrs490/Rrs555, well simulates the sigmoidal pattern evident between log-transformed radiance ratios and chlorophyll, and has been chosen as the at-launch SeaWiFS operational chlorophyll a algorithm. Improved performance was obtained using the ocean chlorophyll 4 algorithm (OC4), a four-band (443, 490, 510, 555 nm), maximum band ratio formulation. This maximum band ratio (MBR) is a new approach in empirical ocean color algorithms and has the potential advantage of maintaining the highest possible satellite sensor signal: noise ratio over a 3-orders-of-magnitude range in chlorophyll concentration.

/pdf/ocean-color-chlorophyll-algorithms-for-seawifs-68regm2asj.pdf

Ocean Color Chlorophyll Algorithms for SEAWIFS

SBDART is a software tool that computes plane-parallel radiative transfer in clear and cloudy conditions within the earth's atmosphere and at the surface. All important processes that affect the ultraviolet, visible, and infrared radiation fields are included. The code is a marriage of a sophisticated discrete ordinate radiative transfer module, low-resolution atmospheric transmission models, and Mie scattering results for light scattering by water droplets and ice crystals. The code is well suited for a wide variety of atmospheric radiative energy balance and remote sensing studies. It is designed so that it can be used for case studies as well as sensitivity analysis. For small sets of computations or teaching applications it is available on the World Wide Web with a user-friendly interface. For sensitivity studies requiring many computations it is available by anonymous FTP as a well organized and documented FORTRAN 77 source code.

/pdf/sbdart-a-research-and-teaching-software-tool-for-plane-26av23gjuu.pdf

SBDART: A Research and Teaching Software Tool for Plane-Parallel Radiative Transfer in the Earth's Atmosphere.

We provide tables of theoretical isochrones in several photometric systems. To this aim, the following steps are followed: (1) first, we re-write the formalism for converting synthetic stellar spectra into tables of bolometric corrections. The resulting formulas can be applied to any photometric system, provided that the zero-points are specified by means of either ABmag, STmag, VEGAmag, or a standard star system that includes well-known spectrophotometric standards. Interstellar ab- sorption can be considered in a self-consistent way. (2) We assemble an extended and updated library of stellar intrinsic spectra. It is mostly based on "non-overshooting" ATLAS9 models, suitably extended to both low and high eective temperatures. This oers an excellent coverage of the parameter space of Te ,l ogg ,a nd (M/H). We briefly discuss the main uncertainties and points still deserving more improvement. (3) From the spectral library, we derive tables of bolometric corrections for Johnson- Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey systems (this latter consisting on the WFI, EMMI, and SOFI filter sets). (4) These tables are used to convert several sets of Padova isochrones into the corresponding absolute magnitudes and colours, thus providing a useful database for several astrophysical applications. All data files are made available in electronic form.

/pdf/theoretical-isochrones-in-several-photometric-systems-i-c9hmqlmbsa.pdf

Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets

Results are presented, which follow from the merging of: (a) our previously published absolute integrals of the disk-center intensity for 20 A wide spectral bands; (b) the ratios of mean to central intensity derived from recent observations of the center-to-limb variation of those bands (λ 6600 A); (d) the high resolution Fourier transform spectra obtained by J. Brault at Kitt Peak for the disk-center and the irradiance; (e) some further auxiliary data, which served mainly to eliminate the local perturbations caused by lines of telluric molecular bands. The main result is the presentation of high precision radiation data for both the integrated disk and the disk-center, concerning the line-averaged radiation and the continuum (in UV: highest ‘window’-intensities) as well. The internal accuracy (the ‘scatter’) should not be worse than that of the FTS spectra, which is less than 0.2% (mean error); local systematic deviations exceeding 0.5% are not to be expected. The absence of a significant systematic error - neutral or wavelength-dependent - has been proven already elsewhere.

The solar radiation between 3300 and 12500 Å

The conversion of our centre of disk intensities published in 1968/70 into mean disk intensities has been repeated, using more accurate data for the centre-to-limb variation of both continuous radiation and strong absorption lines.

Improved Data of Solar Spectral Irradiance from 0.33 to 1.25 μ

The Sun's limb darkening was observed repeatedly between the 1986 minimum and the 1990 maximum of solar activity.Systematic variations, which could depend either on the momentary activity and/or the phase in the solar cycle, werenot detectable, either at continuum wavelengths or in two broad-band spectral intervals. Completelyirregular variations, which concern not only individual, successive scans (due to granulation, etc.), but also thedaily andseasonal averages, are usually less than 1%, but can reach occasionally 2% or even more. Minoreast-west asymmetries even in the seasonal means seem to be well established, mainly for λ < 400 nm. Thefinal, mean limb-darkening coefficients agree basically with those published by Pierce and Slaughter (1977) and Pierce, Slaughter, and Weinberger (1977), but show a much lower scatter when plotted against wavelength.

Solar limb darkening 1986–1990 (λλ303 to 1099 nm)

Corrections are given which transform the Tables of the solar radiation data (Labs and Neckel, 1968) into the ‘International Practical Temperature Scale of 1968’. Additionally, for the adjustment of the data of the ‘true continuum’ and the corresponding line blanketing as well, the veiled line effect mentioned first by Carbon et al. (1968), but studied in more detail by Holweger (1970a), has been considered also. The corresponding corrections of the solar irradiance result in an improved value of the spectrophotometric solar constant: S = 1.947 cal cm-2 min-1 or 0.1358 W cm-2. Two Tables presenting the ‘highest (window-) intensities’ and the corrected irradiance data have been added.

Transformation of the absolute solar radiation data into the ‘International Practical Temperature Scale of 1968’

A detailed compilation of the most recent values of the solar constant is given (13 values published from 1967 to 1970). The most probable value seems to be 1.95 cal cm−2 min−1 or 1.36 kW m−2 with a formal rms error of ± 0.3%. The corresponding effective temperature is 5770K. Systematic errors of the order of ± 1%, but also a possible variability of the same order cannot be excluded.

Dietrich Labs

Papers

The solar radiation between 3300 and 12500 Å

Improved Data of Solar Spectral Irradiance from 0.33 to 1.25 μ

Solar limb darkening 1986–1990 (λλ303 to 1099 nm)

Transformation of the absolute solar radiation data into the ‘International Practical Temperature Scale of 1968’

The Solar Constant (A Compilation of Recent Measurements)