Dependence Of Albedo Research Articles

Mercury's Atmosphere from Mariner 10: Preliminary Results

Analysis of data obtained by the ultraviolet experiment on Mariner 10 indicates that Mercury is surrounded by a thin atmosphere consisting in part of helium. The partial pressure of helium at the terminator is about 5 x 10(-12) millibar. The total surface pressure of the atmosphere is less than about 2 x 10(-9) millibar. Upper limits are set for the abundance of various gases, including hydrogen, oxygen, carbon, argon, neon, and xenon. The wavelength dependence of Mercury's surface albedo is similar to that of the moon over a broad range of wavelengths from 500 to 1600 angstroms. Strong signals were recorded by the airglow instrument as Mariner 10 passed through the cavity behind Mercury. They are as yet unexplained but may provide information on the properties of the local plasma.

Numerical evaluation of the azimuthally dependent albedo problem in slab geometry

The azimuthal dependence of the neutron transport equation in a plane geometry is treated by a Fourier decomposition. The solution to the slab albedo problem is obtained by expansion of the azimuthal dependence of the angular flux into an infinite Fourier cosine series resulting in a finite set of uncoupled, azimuthally symmetric slab albedo problems. The Fourier coefficients of the angular flux are shown to satisfy a modified transport equation which can readily be solved numerically with existing codes. Numerical results are presented for a one-speed example problem, and a comparison of a ten-group calculation with an experimental transmission spectrum is given.

Dependence of normal albedo of lunar regions on wavelength

Normal albedos of thirteen lunar regions are determined at five wavelengths between 4000 and 8000 A. The deduced values agree with those of the previous investigators except those given by Gehrelset al. (1964) and Van Diggelen (1965). They increase monotonically with the wavelength. At the shortest wavelength, a slight enhancement is detected for most of the regions observed.

The Wavelength Dependence of the Albedos of Uranus and Neptune from 0.3 to 1.1 Micron

view Abstract Citations (31) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Wavelength Dependence of the Albedos of Uranus and Neptune from 0.3 to 1.1 Micron Wamsteker, Willem Abstract Narrow-band photoelectric photometry was made of Uranus and Neptune over a wavelength interval from 0.3 to 1.1 . The wavelength dependence of the geometric albedo was determined for these planets. Evidence is given that the comparison star used resembles the Sun very closely in its energy distribution. It is shown that, apart from methane, another opacity source seems to be necessary in the atmospheres of these planets to explain the observed wavelength dependence of the geometric albedo for the two planets simultaneously. Radiative transfer calculations were made to determine if the previously suggested pressure-induced dipole absorptions of H2 result in a self-consistent explanation. This seems to be the case. The H2 abundance in this case is limited for both planets between 350 km amagat < N(H2) < 800 km amagat. This agrees with a previous determination of the H2 abundance for Uranus. The relative CH4 abundance is determined from the observations to be N (CH4)/Nw(CH4) > 1; the actual value depends on the saturation in the absorptions. This does not agree with previous determinations. Subject headings: atmospheres, planetary - Neptune - photometry - Uranus Publication: The Astrophysical Journal Pub Date: September 1973 DOI: 10.1086/152387 Bibcode: 1973ApJ...184.1007W full text sources ADS |

Surface albedo at a tower site in Lake Ontario

Measurements of incoming global, diffuse and reflected radiation at a tower site in Lake Ontario are used to evaluate components of surface albedo. Albedo for diffuse radiation lies between 0.074 and 0.082 and a coefficient for backscatter from sub-surface water layers shows little deviation from a mean of 0.017. Direct beam albedo for a calm surface follows the Fresnel law. Waves increase direct-beam albedo particularly at higher solar zenith angles. A pronounced dependence of albedo upon zenith angle for clear skies decreases with increasing cloud amount and becomes undetectable in overcast conditions. On a daily basis, albedo ranged between 0.07 in early July to 0.11 in mid-November. Day-to-day scatter is within ±1% of the mean seasonal trend.

Ocean Color Determination Through a Scattering Atmosphere

Measurements made of the surface level albedo for ocean water containing various concentrations of phytoplankton indicate a strong correlation between wavelength dependent albedo ratios and phytoplankton chlorophyll concentration. To sense surface level albedo ratios from space platforms it is necessary to correct for the scattering and absorption properties of the atmosphere for the wavelengths in question. Atmospheric scattering models were constructed to calculate corrections at two wavelengths, 0.46 mum and 0.54 mum. The relationship between albedo ratios at the top of the atmosphere and at surface level was made for several different aerosol optical depths. Assuming a natural background uncertainty in the aerosol optical depth of 0.1 it is found that the chlorophyll concentration may be determined to within one standard deviation of from 0.5 mg to 2.5 mg/m(3), depending upon the solar zenith angle at the time of measurement. By remotely sensing the aerosol optical depth to a greater accuracy it appears feasible to detect chlorophyll concentrations to an uncertainty approaching 0.1 mg/m(3).

The albedo of a pine forest

AbstractThe albedo of a pine forest was measured for a total of 243 hours during the summer of 1970 by pairs of Kipp solarimeters whose output was recorded by a computer controlled data acquisition system. It was found that the mean albedo was 9.1 per cent. On cloudless days there was a pronounced dependence of albedo on solar zenith angle; however, on cloudy days there was little variation. The effect on the albedo of the wetness of the canopy was less than one per cent except at large solar zenith angles. The mean albedos for June and December were calculated and found to be 8.9 and 11.7 per cent respectively.

Polarization and Albedo

SCHWERDTFEGER1 has recently directed attention to the mechanism underlying the dependence of short-wave or optical albedo on solar elevation and the presence or absence of cloud cover. He cites as one of the major causes of this dependence the polarization of incident radiation (solar) on reflexion at terrestrial surfaces. The few comments made here are intended to bring out the rather involved interrelation between polarization and albedo, which plays a very prominent part in the solution of radiant -energy transfer problems in the Earth's atmosphere.