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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
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NASA NTRS1984

Stratocumulus simulations with a general circulation model

Stratus and stratocumulus cloud sheets which are among the most common cloud types over the world are discussed. They are characteristic of the undisturbed subtropical marine boundary layer over the eastern oceans, where cool water and large scale sinking motion suppress penetrative cumulus convection. They also occur over the Arctic Ocean, particularly in summer, and behind cold outbreaks over the western oceans in winter. Observational studies were conducted and further observations are planned.

Randall, D. A.↗
NASA NTRS1984

The sensitivity of a general circulation model to Saharan dust heating

During the Northern summer, sporadic outbreaks of wind borne Saharan dust are carried out over the Atlantic by the tropical easterlies. Optical depths due to the dust can reach 3 near the African coast, and the dust cloud can be detected as far west as the Caribbean Sea (Carlson, 1979). In order to obtain insight into the possible effects of Saharan dust on the weather and climate of North Africa and the tropical Atlantic Ocean, simulation experiments have been performed with the Climate Model of the Goddard Laboratory for Atmospheric Sciences. The most recent version of the model is described by Randall (1982). The model produces realistic simulations of many aspects of the observed climate and its seasonal variation.

Randall, D. A.↗
NASA NTRS1983

A study of the kinetic energy generation with general circulation models

The history data of winter simulation by the GLAS climate model and the NCAR community climate model are used to examine the generation of atmospheric kinetic energy. The contrast between the geographic distributions of the generation of kinetic energy and divergence of kinetic energy flux shows that kinetic energy is generated in the upstream side of jets, transported to the downstream side and destroyed there. The contributions from the time-mean and transient modes to the counterbalance between generation of kinetic energy and divergence of kinetic energy flux are also investigated. It is observed that the kinetic energy generated by the time-mean mode is essentially redistributed by the time-mean flow, while that generated by the transient flow is mainly responsible for the maintenance of the kinetic energy of the entire atmospheric flow.

Chen, T.-C.↗
NASA NTRS1984

Numerical experiments with a general circulation model concerning the distribution of ozone in the stratosphere

The distribution of ozone below 60 km altitude has been simulated in two experiments employing a nine-layer quasi-geostrophic spectral model and linear parameterization of ozone photochemistry, the first of which included thermal and orographic forcing of the planetary scale waves, while the second omitted it. The first experiment exhibited a high latitude winter ozone buildup which was due to a Brewer-Dodson circulation forced by large amplitude (planetary scale) waves in the winter lower stratosphere. Photochemistry was also found to be important down to lower altitudes (20 km) in the summer stratosphere than had previously been supposed.

Kurzeja, R. J.↗
NASA NTRS1983

The sensitivity of a general circulation model to Saharan dust heating

Evidence is accumulating that tropospheric aerosols, such as Saharan dust, can significantly influence weather and climate. The Climate Model of the Goddard Laboratory for Atmospheric Sciences is presently used to assess the possible effects of Saharan dust on the weather and climate of North Africa and the tropical Atlantic Ocean. The three-dimensional model solves the conservation equations for the horizontal wind vector, potential temperature, water vapor mixing ratio, and surface pressure. Parameterizations are included for turbulent exchange at the earth surface, cumulus convection, large scale saturation, diurnally varying solar radiation, and terrestrial radiation. Realistic simulations are thereby produced for many aspects of the observed climate.

Randall, D.↗
NASA NTRS1983

Stratocumulus simulation with a general circulation model

Stratus and stratocumulus cloud sheets which are among the most common cloud types over the world are discussed. They are characteristic of the undisturbed subtropical marine boundary layer over the eastern oceans, where cool water and large scale sinking motion suppress penetrative cumulus convection. They also occur over the Arctic Ocean, particularly in summer, and behind cold outbreaks over the western oceans in winter. Observational studies were conducted and further observations are planned.

Randall, D. A.↗
NASA NTRS1986

Global analysis of ocean surface wind and wind stress using a general circulation model and Seasat scatterometer winds

Instantaneous and 15-day time-averaged fields of surface wind, wind stress, curl of the wind stress, and wind divergence are presented. These fields are derived from the Goddard Laboratory for Atmospheres four-dimensional analysis/forecast cycle, for the period September 6-30, 1978, using conventional data, satellite temperature soundings, cloud-track winds, and subjectively dealiased Seasat scatterometer winds.

Kalnay, E.↗
NASA NTRS1986

Cloud radiative forcing in a general circulation model

Preliminary results are reported from a simulation carried out with the UCLA/Goddard GCM to investigate cloud radiative forcing phenomena. Of particular interest was cloud feedback, i.e., the changes in forcing brought about by climate change. Early results indicate that clouds cool the tropical oceans and land surface and warm the tropical atmosphere.

Randall, D. A.↗
NASA NTRS1986

Cloud and radiation experiments with a general circulation model

Interactions between cloud fields and radiation fields in GCM simulations were examined with June-July simulations with the UCLA/Goddard GCM. Modified radiation parameterizations for longwave and shortwave transfer were made to the GCM. The model generated supersaturation, boundary layer and convective clouds. The simulations were configured to consider the absence of water vapor absorption in the longwave parameterization, no appearance of anvils, and no detrainment of liquid water.

HARSHVARDHAN↗
NASA NTRS1986

The structure and propagation of intraseasonal oscillations appearing in a GFDL general circulation model

The 12-year output of a 15-wavenumber GCM experiment is analyzed, with the objective of describing the spatial and temporal behavior of dominant intraseasonal variations. The parameters analyzed include five-day averages of wind, geopotential height, sea level pressure, and precipitation. It is demonstrated that the spatial structure, propagation characteristics, and seasonal dependence of the model features are consistent with observations reported in the literature. The model findings are interpreted in terms of the current theoretical understanding of tropical and extratropical motions.

Lau, Ngar-Cheung↗
NASA NTRS1987

Atmospheric distribution of Kr-85 simulated with a general circulation model

A three-dimensional chemical tracer model for the troposphere is used to simulate the global distribution of Kr-85, a long-lived radioisotope released at northern midlatitudes by nuclear industry. Simulated distributions for the period 1980-1983 are in excellent agreement with data from six latitudinal profiles measured over the Atlantic. High concentrations of Kr-85 are predicted over the Arctic in winter, advected from European sources, and somewhat smaller enhancements arising from the same sources are predicted over the tropical Atlantic in summer. Latitudinal gradients are steepest in the northern tropics, with distinctly different seasonal variations over the Pacific, as compared to the Atlantic. The global inventory of Kr-85 is reconstructed for the period 1980-1983 by combining the concentrations measured over the Atlantic with the global distributions predicted by the model. The magnitude of the Soviet source is derived. The interhemispheric exchange time is calculated as 1.1 years, with little seasonal dependence.

Jacob, Daniel J.↗
NASA NTRS1987

Jet stream velocity errors in general circulation models

The longitude and time dependence of excessive wind speed errors above subtropical jets in current GCM forecasts is studied for 14 five-day winter forecasts using the NASA Goddard Laboratory for Atmospheres fourth-order GCM. Several distinct phenomena, which may be divided into four categories, are found to contribute to the excess winds. These categories are: (1) error growth above the jet near the Himalayas; (2) error growth above the jet initiated elsewhere followed by advection; (3) tropical moisture bursts appearing in equatorial regions and migrating northeastward to merge with and distort the jet; and (4) undulatory growth of waves in the meridional component of the jet stream velocity. The results of additional sensitivity studies of the Himalayan region error are also reported.

Tenenbaum, J.↗
NASA NTRS1989

Cross correlations between the radiation and atmospheric variables in a general circulation model and satellite data

The classical picture of the influence of midlatitude troughs on cloud patterns is studied in a GCM and in satellite and NMC data, by comparing the cross correlation of the poleward component of the wind and the outgoing longwave radiation (OLR). Over storm tracks, the variance of the OLR is explained by a correlation with the poleward component of the horizontal wind, forced by stronger correlations with the vertical velocity through the cloud and humidity fields. It is found that stratiform clouds have a dominant impact on the model OLR fluctuations, even over much of the tropics.

Charlock, Thomas P.↗
NASA NTRS1988

Diurnal variability of the planetary albedo - An appraisal with satellite measurements and general circulation models

An atmospheric radiation model is used here to illustrate several features associated with modeling the diurnal cycle of the planetary albedo. It is found that even for clear regions there appear to be deficiencies in our knowledge of how to model this quantity. The diurnal amplitude factor, defined as the ratio of the diurnally averaged planetary albedo to that at noon, between two GCMs and measurements made from a geostationary satellite. While reasonable consistency is found, the comparisons underscore difficulties associated with converting local-time albedo measurements, as made from sun-synchronous satellites, to diurnally averaged albedos.

Potter, G. L.↗