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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 127 records · Page 7
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NASA NTRS1988

An earth outgoing longwave radiation climate model. II - Radiation with clouds included

The model of the outgoing longwave radiation (OLWR) of Yang et al. (1987) is modified by accounting for the presence of clouds and their influence on OLWR. Cloud top temperature was adjusted so that the calculation agreed with NOAA scanning radiometer measurements. Cloudy sky cases were calculated for global average, zonal average, and worldwide distributed cases. The results were found to agree well with satellite observations.

Yang, Shi-Keng↗
NASA NTRS1989

A ten-year monthly data set of outgoing longwave radiation from Nimbus-6 and Nimbus-7 satellites

Monthly mean outgoing longwave radiation (OLR) measurements in the form of global contour maps and coefficients of spherical-harmonic functions for each month of the 10-year period, July 1975 through October 1985, have recently been completed. One data set contains three years (July 1975 to June 1978) of 'continuous' data from the wide field-of-view sensor of the Earth Radiation Budget experiment (ERB) aboard the Nimbus-6 satellite. The other data set contains seven years (November 1978 to October 1985) of 'continuous' data from the ERB experiment aboard the Nimbus-7 satellite. The OLR broadband time series could be used, for example, to study the interannual variability of OLR. An example is given of two El Ninos that occurred in the 10-year timeframe.

Bess, T. Dale↗
NASA NTRS1989

A parameterization for longwave surface radiation from sun-synchronous satellite data

A parameterization is presented for computing downward, upward, and net longwave radiation at the earth's surface using data from NOAA sun-synchronous satellites. The parameterization is applied to satellite soundings for April, 1982 over a large region of the tropical Pacific Ocean. Sensitivity studies were used to estimate the random and systematic errors in computed fluxes due to probable errors in TOVS-derived parameters. It is suggested that large biases in the results due to errors in TOVS-derived parameters may be corrected with data from the International Satellite Cloud Climatology Project.

Gupta, Shashi K.↗
NASA NTRS1988

Relationships between sea surface temperature and outgoing longwave radiation over the tropical oceans

The spatial relationships between convection and SST at intraseasonal, seasonal, and interannual timescales over the tropical oceans are studied. The dependence of these local relationships on large-scale surface convergence/divergence is determined. The data used are day and night averaged NOAA outgoing longwave radiation (OLR) and Climate Analysis Center monthly SSTs based on in situ measurements. Below 28 C, the SST and OLR have an approximately linear relationship. Above 28 C, the relationship between the SST and convection may be much more complex.

Chan, Paul H.↗
NASA NTRS1989

An intercomparison of longwave measurements by ERBE radiometers on the NOAA-9 and ERBS satellites

Two instrument modules of each satellite on which the Earth Radiation Budget Experiment (ERBE) is orbiting observe components of the earth radiation budget with three different scales of earth view. An intercomparison of longwave measurements by these instruments provides relative information concerning radiometric performance at satellite altitude, techniques of estimating upwelling exitances, and an end-to-end evaluation of the data processing system. Results indicate that the ERBE radiometers are mildly sensitive to varying thermal loads from the spacecraft and/or the earth-space environment. Radiometric variations at the satellite and methods of data interpretation contribute about equally to the uncertainty of radiant exitances from the earth.

House, Frederick B.↗
NASA NTRS1989

Longwave spectral dependence of emission from warm dust clouds

Observations of the continuum emission from warm dust clouds at 230 GHz, or 1300 microns, enables the determination of the frequency dependence of the optically thin longwave emission. Integrating the emission over the solid angle of the clouds gives a flux independent of the beam size and of the internal temperature structure of the clouds. The frequency resolving power of 64 allows the correction of these fluxes for the contribution of free-free emission from nearby H II regions at a price of reduced sensitivity. These observations were combined with similar observations made by others in the submillimeter and far infrared regimes to determine the continuum spectra of the dust clouds. Mean characteristics were determined for these clouds, fitting the spectra with simple transfer equations. Results are briefly discussed.

Gordon, M. A.↗
NASA NTRS1990

The relationship of extratropical outgoing longwave radiation to monthly geopotential teleconnection patterns

The relationship between low frequency variations in extratropical fields of outgoing longwave radiation (OLR) and geopotential teleconnection patterns as determined by rotated principal components analysis of the NMC 500-mb heights is investigated in the Northern Hemisphere. The monthly broadband OLR is obtained from the Nimbus-6 and Nimbus-7 Wide-Field-Of-View radiometer record. Each of the main 500-mb teleconnection patterns has a characteristic signal in the OLR field for the month in which the 500-mb pattern occurs. The OLR signals mark cloud and diabatic heating events that are associated with the teleconnection patterns. A demonstration is given of correlation between extratropical monthly OLR and geopotential height. Coupled with the expected tropospheric response to radiation on monthly time scale. This demonstration stresses the importance of the radiation simulation in model studies of the low frequency variability of atmospheric circulation. The extratropical OLR does not appear to be a useful predictor for the 500-mb teleconnection patterns on a monthly time scale.

Charlock, Thomas P.↗
NASA NTRS1991

Diurnal variations of outgoing longwave radiation and albedo from ERBE scanner data

The scanning instruments of the Earth Radiation Budget Experiment provide measurements of instantaneous broadband albedo and outgoing longwave radiation (OLR) with a spatial resolution of about 50 km. Data from the Earth Radiation Budget Satellite (ERBS), which is in an orbit that precesses through local time at the rate of one hour every three days, can be used to describe the mean, hourly diurnal variations in the distribution of OLR and albedo on this scale. Much of this variation is caused by cloud type and amount changes. Two-dimensional histograms show the coevolution of OLR and albedo with the diurnal cycle, and the distribution of albedo-OLR pairings associated with the cloud distribution in a particular region and season. The albedo-OLR pairing characterizes a cloud type and determines its net effect on the energy balance at the top of the atmosphere. Diurnal variations in cloud type and amount in many regions are sufficient to cause substantial errors in radiation budget quantities and cloud properties estimated from observations taken from a single sun-synchronous orbit. Errors in estimated net radiation can be as large as 50 W/sq m for oceanic stratus regions and for land regions during summer.

Hartmann, Dennis L.↗
NASA NTRS1990

Differences in the day and night longwave fluxes at satellite altitude for sun-synchronous NOAA-9 nonscanning sensors

The outgoing LW flux determined by using the data measured by four nonscanning sensors at satellite altitude is reported. The outgoing LW fluxes for MFOV and WFOV sensors at satellite altitude are determined by subtracting the SW fluxes from the total sensors. Results for 1985 and 1986 are discussed. The nighttime LW flux determined by using the MFOV-T channel at the satellite altitude is found to be constant from month to month within 1 W/sq m, while the LW flux from WFOV-T channel varies within 2 to 3 W sq m. The high value for the WFOV-T channel is attributed to the effects of sun-blips on the measurements involved. The main advantage of using day/night longwave flux differences at satellite altitude is that the consistencies of nonscanner sensors can be checked very quickly.

Pandey, Dhirendra K.↗
NASA NTRS1991

Spatial variability of outgoing longwave radiation

Spatial distributions of day-to-day variations in the outgoing longwave radiation (OLR) are quantified by examining spatial variations in daily OLR data obtained from the Earth Radiation Budget Experiment scanning radiometer aboard the NOAA-9 meteorological satellite, in the form of daily maps and monthly radiation maps at 2.5 deg latitude-longitude scale. The results show that the variations of OLR during a month are markedly greater in the subtropics than they are in the mid and high altitudes. Results for October 1985 are presented.

Smith, G. L.↗
NASA NTRS1992

A parameterization for longwave surface radiation from satellite data - Recent improvements

Several improvements have been made recently to the parameterization for surface longwave radiation described by Gupta (1989). Model constants have been modified in order to use meteorological data from the International Satellite Cloud Climatology Project instead of from the TIROS Operational Vertical Sounder data, primarily to take advantage of the vastly superior cloud information available from the former. Additional modifications were made to improve the estimation of cloud effect in the presence of low-level clouds. The latter modifications reduced the systematic error of the overcast-sky fluxes from 10.0 to 1.7 W/sq m and the random error from +/- 18.9 to +/- 6.3 W/sq m when compared to the fluxes computed with a detailed radiative transfer model.

Gupta, Shashi K.↗
NASA NTRS1993

Longwave surface radiation over the globe from satellite data - An error analysis

Errors have been analyzed for monthly-average downward and net longwave surface fluxes derived on a 5-deg equal-area grid over the globe, using a satellite technique. Meteorological data used in this technique are available from the TIROS Operational Vertical Sounder (TOVS) system flown aboard NOAA's operational sun-synchronous satellites. The data used are for February 1982 from NOAA-6 and NOAA-7 satellites. The errors in the parametrized equations were estimated by comparing their results with those from a detailed radiative transfer model. The errors in the TOVS-derived surface temperature, water vapor burden, and cloud cover were estimated by comparing these meteorological parameters with independent measurements obtained from other satellite sources. Analysis of the overall errors shows that the present technique could lead to underestimation of downward fluxes by 5 to 15 W/sq m and net fluxes by 4 to 12 W/sq m.

Gupta, S. K.↗
NASA NTRS1993

Comparison of the Highly Reflective Cloud and Outgoing Longwave Radiation datasets for use in estimating tropical deep convection

Two currently existing long-term satellite-derived data sets (the Highly Reflective Cloud (HRC) and the Outgoing Longwave Radiation (OLR) data sets) were compared for the accuracy in estimating tropical deep convection, in terms of their climatological and frequency-dependent characteristics, their consistency in identifying deep tropical convection, and their relationship to local sea surface temperature (SST). The results reveal some important differences between the HRC and OLR data sets in terms of their temporal and spatial scales of variability, their relationships to other geophysical fields, and the logistics of their use. It was found that, for many applications, the HRC data set represents the characteristics of the cloud cluster-scale tropical convection more accurately than the OLR data set.

Waliser, Duane E.↗
NASA NTRS1993

Heating, moisture, and water budgets of tropical and midlatitude squall lines - Comparisons and sensitivity to longwave radiation

A 2D time-dependent and nonhydrostatic numerical cloud model is presently used to estimate the heating, moisture, and water budgets in the convective and stratiform regions for both a tropical and a midlatitude squall line. The model encompasses a parameterized, three-class ice phase microphysical scheme and longwave radiative transfer process. It is noted that the convective region plays an important role in the generation of stratiform rainfall for both cases. While a midlevel minimum in the moisture profile for the tropical case is due to vertical eddy transport in the convective region, the contribution to the heating budget by the cloud-scale fluxes is minor; by contrast, the vertical eddy heat-flux is relatively important for the midlatitude case due to the stronger vertical velocities present in the convective cells.

Tao, W.-K.↗
NASA NTRS1992

Comparison of 18 months of longwave radiation results from Nimbus-7 and the ERBE NOAA-9 and NOAA-10 satellites

The outgoing longwave radiation (OLR) data from ERBE wide-field-of-view (WFOV) and scanning sensor are compared with Nimbus-7 WFOV results. Monthly averaged OLR data from the ERBE WFOV instruments aboard the NOAA-9 and NOAA-10 polar orbiting satellites during the 3-year overlap period with Nimbus-7 are deconvolved using spherical harmonics. Results of a comparison of the data sets are presented on regional, zonal, and global scales in the spatial domain and on a monthly scale in the time domain.

Bess, T. D.↗
NASA NTRS1993

Earth radiation budget - Results of outgoing longwave radiation from Nimbus-7, NOAA-9, and ERBS satellites

Outgoing longwave radiation (OLR) data from Nimbus-7 ERB wide field-of-view instruments are compared with results from the ERBE instruments aboard the NOAA-9 and NOAA-10 satellites. Over most regions of the globe, the agreement between the two sets of OLR results is generally to within 8 W/sq m. There are larger differences at higher latitudes and regions concentrated over land and desert. Results of daytime and nighttime differences suggest that the shortwave channels may be at fault due to their different design for Nimbus-7 and NOAA-9. Some of the differences may also be related to different viewing geometry of the two satellites.

Bess, T. D.↗
NASA NTRS1994

Spatial variability of outgoing longwave radiation

Data from the Earth Radiation Budget Experiment scanning radiometer aboard the NOAA-9 operational meteorological satellite are used to investigate the spatial variability of Outgoing Longwave Radiation (OLR). Daily and monthly radiation maps at 2.5 deg latitude-longitude scale are used as a basis for the study. The regions of greatest variability are in the tropics and subtropics. Storm tracks such as the South Pacific convergence zone appear as regions of high OLR variability. Spatial spectra in longitude show two regimes of OLR. At large scales (wavenumbers less than 6), the spatial spectrum is flat. For wavenumbers greater than 10, the spectra decrease as wavenumber to the -3 power. The spatial spectrum of daily anomalies from the mean is a strong function of latitude and season, with interesting features. Correlations of daily anomalies from the monthly mean decrease exponentially in latitude but have a damped-wave structure in longitude. The spatial variability of the daily maps, as measured by degree variance, have 10 times the power at degree 24 than the monthly maps, but at scales between 1 and 10, the degree variance is practically the same for daily as for monthly.

Smith, G. Louis↗
NASA NTRS1994

Validation of a technique for estimating outgoing longwave radiation from HIRS radiance observations

Simultaneous observations by the Earth Radiation Budget Experiment (ERBE) scanning radiometer and the High-Resolution Infrared Sounder (HIRS) on board the NOAA-9 spacecraft have been used to validate a multispectral technique for estimating the outgoing longwave radiation (OLR) from the earth-atmosphere system. Results from approximately 100 000 collocated observations show that the HIRS technique provides instantaneous OLR estimates that agree with the ERBE observations just as well as different ERBE scanners agree with each other--about 5 W m(exp -2) rms. Although there are differences between the HIRS and ERBE estimates that depend upon the scene type and time of day, the HIRS technique explained more than 99% of the variance of the ERBE observations for both day and night observations. The results suggest that the HIRS OLR technique is a suitable replacement for the Advanced Very High Resolution Radiometer technique now used by the National Oceanic and Atmospheric Administration for operational estimates of the OLR.

Ellingson, Robert G.↗