Showing papers on "Haze published in 1970"

Vertical-attenuation model with eight surface meteorological ranges 2 to 13 kilometers

Abstract: : An examination of the haze regime shows that: (l) the aerosol properties of a surface meteorological range generally affect a mixing layer to 5 km altitude, and (2) the lower and upper visibility limits of a haze regime are defined by meteorological ranges 1.2 km and 15 km respectively. Within these limits eight meteorological ranges are selected for developing uv, visible, and ir aerosol attenuation coefficients. An aerosol scale height is derived for each meteorological range. Finally, the computed aerosol attenuation coefficients are presented as tabulations which include previously published attenuation parameters (aerosols, molecules and ozone) to 50 km altitude.

Radon-222 in the North Atlantic Trade Winds: Its Relationship to Dust Transport from Africa

Abstract: The concentration of radon-222 in air was measured during a flight from Miami to Barbados to Dakar and return; concentrations ranged from 1 to 55 picocuries per standard cubic meter of air and were highest in areas of dense haze, which were present along most of the flight path across the Atlantic Ocean. The haze is attributed to dust originating from the arid regions of western Africa. Radon-222 may be useful as a tracer for African air parcels over the equatorial Atlantic.

Relationships between vertical attenuation and surface meteorological range.

Abstract: An examination of the haze regime, used in the sense of diminished surface meteorological range, shows that the lower and upper limits can be defined by meteorological ranges 1.2 km and 15 km, respectively. In order to develop relationships between surface haze and vertical attenuation, eight meteorological ranges are selected from within these limits; then, vertical aerosol attenuation parameters are computed by deriving an aerosol scale height for each meteorological range. A sample tabulation for one of twenty wavelengths in the uv, visible, and ir is presented and combined with previously published attenuation parameters (aerosols, molecules, and ozone) to the 50-km altitude.

Contribution to the turbidity problem in Mexico City

Abstract: The authors give a numerical solution of Angstrom's equation for the extinction of solar radiation, where the procedure involves as variables: the intensityI of direct solar radiation, the optical air massm, the precipitable water contentw, and the Schuepp's turbidity coefficentB; given three of the above variables initially together with the wavelength exponenta as initial conditions, then the solution of Angstrom's equation gives explicitly the fourth variable. In this form a complete description of the atmospheric turbidity is achieved. Two large series of pyrheliometric observations made at Mexico City under very different sky conditions are used (1911–1928 and 1957–1962); the influence on turbidity values of haze, “smog”, fog and clouds is taken into account; the diurnal variation of atmospheric turbidity is also discussed; finally the great influence of volcanic eruptions on atmospheric turbidity is demonstrated.

Thermal Emission from Haze and Clouds

Abstract: The photons thermally emitted by the atmospheric molecules and aerosols as well as those emitted by the planetary surface are followed by a Monte Carlo technique through subsequent collisions with the aerosols and planetary surface. Anisotropic single scattering functions typical of hazes or of nimbostratus clouds are used. The angular variation of the radiation at both the top and bottom of the atmosphere are studied as a function of the single scattering albedo, size distribution of aerosols, optical thickness of the atmosphere, albedo and temperature of planetary surface, and the temperature distribution in the atmosphere.

An explanation for the worldwide anomaly in the concentration of ozone above 40 km

Abstract: It is pointed out that the anomalous seasonal variation in the worldwide ozone concentration above 40 km deduced from Umkehr measurements is opposite to the seasonal variation in atmospheric turbidity. The maximum and minimum seasonal variation in turbidity is used to estimate a haze correction to an Umkehr observation. From a comparison of ozone concentration deduced from corrected and uncorrected Umkehrs it is noted that 1) increased turbidity reduces the ozone concentration at 45 km, and 2) the maximum seasonal change in turbidity can nearly, if not entirely, account for the maximum seasonal change (about 2 μmb) in ozone concentration at 45 km.