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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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147 records · Page 9

Diurnal cloud variations over South America and the southeastern Pacific

The changing distributions of cloud cover are of particular importance in understanding the general circulation patterns of the Southern Hemisphere, whose prediction is hampered by the sparse sampling of physical qualities. In near-tropical areas, the diurnal solar heating cycle is noted to be directly responsible for many of the observed weather patterns. Among the atmosphere's familiar responses to this heating cycle are afternoon thunderstorms over tropical land areas and the 'burnoff' of morning fog or low stratus near coastal margins. Attention is given to these aspects of the atmospheric adjustment to the daily solar cycle in terms of regional scale mean cloudiness over part of the Southern Hemisphere.

Minnis, P.↗

Relationship between the longwave cloud radiative forcing at the surface and the top of the atmosphere

An analysis is presented which suggests a technique that may be able to circumvent the problem of mapping the global longwave surface radiation budget from space in the presence of clouds. A theoretical framework is given that avoids the explicit computation of cloud fraction and the location of cloud base. It is found that in regions where a particular cloud regime exists preferentially, a relationship between the mean long range cloud radiative forcing (CRF) at the top of the atmosphere and at the surface can be shown to exist. Results from a general circulation model suggest that this relationship for monthly means is coherent over fairly large geographical areas. For example, in tropical convective areas, the longwave CRF at the top is very large, but at the surface it is quite small because of the high opacity of the lowest layers of the atmosphere. It is also found that, in areas of stratus over cool ocean surfaces, the longwave CRF at the top is very small but at the surface it is quite substantial.

HARSHVARDHAN↗

Radiative Transfer Models for Deriving Geostationary Broadband Shortwave Radiances Directly from Visible Channels for the Ceres SYN1DEG Product

The Clouds and the Earth's Radiant Energy System(CERES)project was designed to observe the Earth’s radiation budget at the 1° regional and global scale. The CERES instruments on the Terra (10:30 AM local equator crossing time) and Aqua (1:30 PM) satellite may not accurately capture the 24-hour mean flux over regions with systematic diurnal cycles. The Terra-only and Aqua-only derived regional monthly mean SW flux can differ by 25 Wm-2 over maritime stratus and land afternoon convective regions. The CERES project utilizes hourly Geostationary imager (GEO) derived broadband fluxes to more accurately estimate the regional diurnal flux in between CERES measurements. We propose an approach that converts the GEO visible radiance to broadband radiance using RTM radiances that are specific to the individual GEO visible channel spectral response functions. The RTM is first validated using the very spectrally narrow MODIS visible channel and CERES broadband radiances.

geostationary derived broadband radiances↗