Showing papers on "Haze published in 1980"

Cloud and haze properties from Pioneer Venus polarimetry

Abstract: Linear polarization measurements made by the Pioneer Venus orbiter cloud photopolarimeter determined that the low and midlatitude visible clouds mainly contain small H2SO4 droplets with an extensive haze of submicron particles above the cloud group. The polarization of the bright areas poleward of the 55 deg latitude results from the haze which exhibits large spatial and temporal variations. Significant diurnal differences are observed at low latitudes, with more haze close to the morning terminator than near the noon meridian.

Measurements of Visual Range and Radiation-Fog (Haze) Microphysics.

Abstract: An extensive boundary-layer field program was conducted which included simultaneous measurements of visibility and particle size distributions during fog and haze. Several empirical expressions relating changes in visibility to characteristics of the aerosol (droplet) size spectrum and relative humidity are presented and evaluated. Detailed analysis of one evolving dense fog revealed several points of interest regarding the behavior of drop size spectra, including a scheme for approximating fog supersaturation.

Dependence of CO2, aerosol, and ozone concentrations on wind direction at Barrow, Alaska during winter

Abstract: Measurements of CO/sub 2/, aerosol scattering, condensation nuclei, and ozone made continuously at the NOAA baseline observatory at Barrow, Alaska, have been analyzed in conjunction with low-level trajectories of airflow arriving at Barrow during periods from January to March of 1977 and 1978. Ozone concentrations had no dependence on wind direction whereas CO/sub 2/ and aerosol values did show directional dependence; higher values occurred with airflow from the Arctic Basin than with that from the south. The aerosol analyses support the hypothesis that Arctic haze results from advection of aerosols to the Arctic from European or North American anthropogenic sources. CO/sub 2/ results suggest two possible sources for the higher concentrations: transfer from the ocean through annual sea ice to the Arctic atmosphere or advection from midlatitude anthropogenic sources similar to that for the Arctic haze.

Airborne lidar plume and haze analyzer /ALPHA-1/

Abstract: A new two-wavelength airborne lidar system has been constructed and field-tested. The system was designed to observe the distribution of particle concentrations over large regional areas. During a ...

The radius of Titan from Pioneer Saturn data

Abstract: The radius of Titan has been determined from Pioneer Saturn observations taken September 2, 1979. The data sets, one in the red (0.64 µm) and one in the blue (0.44 µm), yield radii of 2840±25 km and 2880±22 km, respectively. The discrepancy between the radius values in the two colors is felt to be the consequence of an optically thin submicron haze above the nominal haze layer. The altitude difference between the red and blue limb is 40±20 km. Using a cloud model derived from the Pioneer Saturn data, the lunar occultation radius (Elliot et al., 1975) has been revised to 2845±40 km, in good agreement with the present result. A lower limit of 1.37 g cm−3 can now be set on Titan's bulk density, using the red radius at the haze top. The actual bulk density probably falls in the range 1.65–1.85 g cm−3 for an atmosphere of 150- to 250-km thickness below the red limb.

The Radius of Titan from Pioneer Saturn Data.

Abstract: The radius of Titan has been determined from Pioneer Saturn observations taken September 2, 1979. The data sets, one in the red (0.64 µm) and one in the blue (0.44 µm), yield radii of 2840±25 km and 2880±22 km, respectively. The discrepancy between the radius values in the two colors is felt to be the consequence of an optically thin submicron haze above the nominal haze layer. The altitude difference between the red and blue limb is 40±20 km. Using a cloud model derived from the Pioneer Saturn data, the lunar occultation radius (Elliot et al., 1975) has been revised to 2845±40 km, in good agreement with the present result. A lower limit of 1.37 g cm−3 can now be set on Titan's bulk density, using the red radius at the haze top. The actual bulk density probably falls in the range 1.65–1.85 g cm−3 for an atmosphere of 150- to 250-km thickness below the red limb.

The Effects of Sunshine, Cloudiness and Haze on Received Ultraviolet Radiation in New York.

Abstract: Ultraviolet data from Rochester, Schenectady and Whiteface Mountain, New York, for the period November 1975-December 1977, have been studied to ascertain the importance of extraterrestrial ultraviolet (UV) radiation, sunshine, cloudiness and haze on received ultraviolet radiation. The first three factors can be shown to have great influence on received UV, while haze cannot be shown to selectively attenuate UV. It appears that there is a linear relationship between sunshine duration and received UV, with a correlation coefficient of 0.88 for the data studied.

Studies on the Influence of Meteorological Parameters on Atmospheric Laser Transmission

Abstract: An experimental and theoretical study on atmospheric laser transmission is given. An in general continuously operating transmissometer measured the attenuation at 10·6 and 0·63 μm over several weeks. Extinction effects at different meteorological conditions, including rain, snow-fall, fog and haze, from measurements and calculations, are presented.

The Parameterization of the Gravitational Water Flux in Fog Models

Abstract: The parameterization of the mean terminal fallspeed of the fog droplets ν has been analyzed in terms of the ratio between the liquid water content and the droplet concentration, W/N, as linked to the gravitational water flux G via G = νW. Computations have been carried out on the basis of 239 experimental droplet size distributions selected from the literature and grouped according to the fog type. The results show that the (ν, W/N) correlation is poor; the values of the correlation coefficients are 0.46, 0.44, 0.48 and 0.56 for valley, advection and radiation fog, and for all the fog types together, respectively. On the other hand, G turns out to be virtually determined by the contribution of the fog droplets (G2) only, while the contribution to G of the haze droplets (G1) is negligible. This result leads us to consider the parameterization of G2 only through a new (ν, W/N) relationship, where ν, W and N are due only to droplets grown on activated condensation nuclei; this new relationship is sh...

The 1978 Denver winter haze study. Volume I. Executive summary. Final report

Abstract: A study of the nature and sources of the Denver winter haze was conducted over a 31-day period in November and December, 1978 Measurements were made of (1) optical properties of the air, (2) physical and chemical properties of suspended particles as a function of size, (3) the important pollutant gases (carbon monoxide, sulfur dioxide, nitrogen oxides, ozone and hydrocarbon vapors), and (4) meteorological parameters including winds, temperature, relative humidity and solar radiation Elemental carbon was found to be the most important contributor (38%) to the particle light extinction coefficient On the average, diesel emissions, natural gas combustion, coal combustion and unidentified sources of elemental carbon each contributed 12 to 15% of the particle extinction coefficient Noncatalyst-equipped automobiles and unidentified sources of organic carbon each contributed 9 to 10% Water, residual oil combustion and catalyst-equipped automobiles contributed about 4% each

Investigation of the Effect of Low Level Maritime Haze on DMSP VHR and LF Imagery

Abstract: : An efficient modeling approach is described to simulate the dependence of remotely sensed radiances at visible and near infrared wavelengths (04.-1.1 microns) on meteorological variables such as relative humidity, wind speed, and visual range. Model elements include: (1) atmospheric opacity due to Rayleigh scattering and gaseous absorption; (2) physical modeling of aerosol size distribution; (3) aerosol optical properties calculations; and (4) implementation of radiative transfer theory. Sensitivity analyses are performed for these variables in the context of examining modeled meteorological influences in the marine environment on the DMSP VHR and LF sensors. The sensitivity of emergent radiances in the near infrared spectral windows to the presence of relative humidity and wind speed dependent coarse mode aerosols of oceanic origin is demonstrated.

Diurnal variations in the spectrum of direct beam visible radiation at urban and rural locations at Milwaukee

Abstract: Measurements of direct beam visible radiation by spectral band on several days during the summer of 1975 at Milwaukee indicate significant variations in urban depletion Diurnal variations in spectral radiation were greatest on moderately polluted days when variations in pollution concentration caused changes in direct beam radiation intensity Lack of variation on slight days was due to particulate concentration consistency, and on dense days to the thickness of the haze layer Wavelengths less than 525 nm were affected most by urban pollutants Afternoon direct beam fluxes were 5–20% lower than morning fluxes on slight and moderate days due to increased particulate concentrations in a more turbulent boundary layer, the result of solar heating On dense days, the reverse situation occurred, with higher afternoon fluxes due to water evaporation from heating the haze layer On all days, differences in direct beam radiation between urban and rural sites was greatest at 400–425 nm (45%) and at least at 700–725 nm (10%), indicating that the effect of the urban area on regional air quality is significant and constant

Qualitative Description of Obscuration Factors in Central Europe

Abstract: : This report qualitatively describes, in elementary terms, the obscuration factors that affect electro-optical (E-O) systems. The obscuration factors are classified into four categories: clear atmosphere, natural obscurants, battlefield obscurants, and land/air interface. Basic radiation laws, Rayleigh and Mie scattering, and the changes that a beam of electromagnetic energy encounters in an atmosphere free from clouds and obstructions to visibility are discussed in the chapter on the clear atmosphere. The effects of fog, rain, snow, drizzle, clouds, haze, and dust storms upon E-O systems are discussed in the chapter on natural obscurants. Battlefield obscurants are dust, smoke, and fire resulting from battle and intentional smoke. The chapter on land/air interface discusses the effect of terrain, vegetation, and ground cover upon obscuration.

Climatic Conditions at Air Force Bases in Australia

Abstract: : The climatic conditions at ground level expected to be encountered at Air Force bases in the Australian Region are tabulated. Mean conditions for each season and the extremes for return periods up to 1000 years are given for temperature, humidity, wind speed and rainfall of various durations as well as information about solar radiation and a number of meteorological conditions including hail, snow, frost, fog, thunder, dust and haze. (Author)

Frequency of Adverse Weather Conditions Affecting High Energy Laser Systems Operations

Abstract: : The planning of high energy laser system operations depends on a knowledge of possible environmental parameters likely to affect the system. Most basically, the planner needs to know the probability that the system will be usable because of adverse weather conditions. The most fundamental environmental conditions inhibiting laser use are high rain rates and low visibility due to fog, haze or dust. This report calculates the frequency of occurrence of these conditions as a function of geographic location. The geographical locations chosen were those which may have possible laser operations, and include the Persian Gulf, North Atlantic, Mediterranean, Southeast Asia, Korea, and the Caribbean Sea. With a limiting 3 hour average rate of 3 mm/hr, the frequency of occurrence of the rain limitation is no greater than 3%. This depends on latitude - higher latitudes having lesser rain rates - as well as time of year. The limiting visibility condition was considered to be 1 km. Visibility less than 1 km was generally related to fog and as such is also related to latitude. In the tropical areas the visibility limitation occurred less than 1% of the time regardless of time of year. In polar and subpolar locales, limited visibility occurred over 20% of the time (Kamchatka, in July).