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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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NASA NTRS1989

Cloud identification for ERBE radiative flux retrieval

A maximum likelihood estimation (MLE) technique to the problem of cloud identification using coarse resolution broadband satellite data is developed and tested using simulated satellite observations. The results suggest that, in the determination of cloud conditions for the inversion of satellite-measured radiances to fluxes, the MLE method is an improvement over a Lambertian earth assumption and the clear/cloud threshold used in the inversion of Nimbus 3 and Nimbus 7 data. The use of the MLE method in the operational processing of Earth Radiation Budget Experiment scanner data is considered.

Wielicki, Bruce A.↗
NASA NTRS1993

Evaluating the design of an Earth Radiation Budget Instrument with systen simulations. Part 1: Instantaneous estimates

A set of system simulations has been performed to evaluate candidate scanner designs for an Earth Radiation Budget Instrument (ERBI) for the Earth Observing System (EOS) of the late 1990s. Five different instruments are considered: (1) the Active Cavity Array (ACA), (2) the Clouds and Earth's Radiant Energy System-Instrument (CERES-I), (3) the Conically Scanning Radiometer (CSR), (4) the Earth Radiation Budget Experiment Cross-Track Scanner (ERBE), and (5) the Nimbus-7 Biaxial Scanner (N7). Errors in instantaneous, top-of-the-atmosphere (TOA) satellite flux estimates are assumed to arise from two measurement problems: the sampling of space over a given geographic domain, and sampling in angle about a given spatial location. When angular sampling errors vanish due to the application of correct angular dependence models (ADMs) during inversion, the accuracy of each scanner design is determined by the instrument's ability to map the TOA radiance field in a uniform manner. In this regard, the instruments containing a cross-track scanning component (CERES-I and ERBE) do best. As errors in ADMs are encountered, cross-track instruments incur angular sampling errors more rapidly than biaxial instruments (N7, ACA, and CSR) and eventually overtake the biaxial designs in their total error amounts. A latitude bias (north-south error gradient) in the ADM error of cross-track instruments also exists. This would be objectionable when ADM errors are systematic over large areas of the globe. For instantaneous errors, however, cross-track scanners outperform biaxial or conical scanners for 2.5 deg latitude x 2.5 deg longitude target areas, providing that the ADM error is less than or equal to 30%. A key issue is the amount of systematic ADM error (departures from the mean models) that is present at the 2.5 deg resolution of the ERBE target areas. If this error is less than 30%, then the CERES-I, ERBE, and CSR, in order of increasing error, provide the most accurate instantaneous flux estimates, within 2-3 W/sq m of each other in reflected shortwave flux. The magnitude of this error is near the 10 W/sq m accuracy requirement of the user community. Longwave flux errors have been found to have the same space and time characteristics as errors in shortwave radiation, but only about 25% as large.

Stowe, Larry↗
NASA NTRS1997

Antarctic Surface Temperatures Using Satellite Infrared Data from 1979 Through 1995

The large scale spatial and temporal variations of surface ice temperature over the Antarctic region are studied using infrared data derived from the Nimbus-7 Temperature Humidity Infrared Radiometer (THIR) from 1979 through 1985 and from the NOAA Advanced Very High Resolution Radiometer (AVHRR) from 1984 through 1995. Enhanced techniques suitable for the polar regions for cloud masking and atmospheric correction were used before converting radiances to surface temperatures. The observed spatial distribution of surface temperature is highly correlated with surface ice sheet topography and agrees well with ice station temperatures with 2K to 4K standard deviations. The average surface ice temperature over the entire continent fluctuates by about 30K from summer to winter while that over the Antarctic Plateau varies by about 45K. Interannual fluctuations of the coldest interannual variations in surface temperature are highest at the Antarctic Plateau and the ice shelves (e.g., Ross and Ronne) with a periodic cycle of about 5 years and standard deviations of about 11K and 9K, respectively. Despite large temporal variability, however, especially in some regions, a regression analysis that includes removal of the seasonal cycle shows no apparent trend in temperature during the period 1979 through 1995.

Comiso, Josefino C.↗
NASA NTRS1971

NOAA's oceanography studies under the Earth Resources Survey Program

Some results are presented of Earth Resources Survey Program studies conducted on: (1) Defining and developing methods of suppressing system noise and cloud contamination in satellite measurements of infrared window radiation. (2) Relating sea surface temperature patterns in the Gulf Stream and Gulf of Mexico to associated thermal front structure with aid of infrared data from Nimbus or ITOS. (3) Testing the feasibility of mapping sea surface roughness and low level wind speed over tropical oceans by means of ATS imagery in sun glitter zones. (4) Microwave radiometer measurements from aircraft and their usefulness and limitations for all-weather mapping of surface roughness, sea ice conditions, and possible surface temperature. (5) Evaluation of scanning radiometer data from ITOS for purposes of mapping snow and ice conditions.

Mcclain, E. P.↗
NASA NTRS1983

Global measurements of sea surface temperature, wind speed and atmospheric water content from satellite microwave radiometry

The Scanning Multichannel Microwave Radiometer (SMMR) was launched on the Seasat and Nimbus 7 satellites in 1978. The SMMR has the ability to measure sea surface temperature and wind speed with the aid of microwaves. In addition, the instrument was designed to measure water vapor and cloud liquid water with better spatial resolution than previous microwave radiometers, and to make sea-ice measurements with higher precision. A description is presented of the results of global analyses of sea surface temperature, wind speed, water vapor, and cloud liquid water, taking into account data provided by the SMMR on the Seasat satellite. It is found that the SMMR data show good self-consistency, and can usefully measure global distributions of sea surface temperatures, surface winds, water vapor, and cloud liquid water.

Njoku, E. G.↗
NASA NTRS1988

Study of the consistency of climatological products of Nimbus-7

The study, in addition to investigating the consistency of climatological products from Nimbus-7 Earth Radiation Budget and Temperature Humidity Infrared Radiometer experiments, focussed on the climatological analysis of the specified regions of the Earth. The climatological study consisted of the effects of various types of clouds on the net radiation, albedos, and emitted radiation. In addition to a correlational study for determining consistency level of data, a population study of the regions was formulated and conducted. The regions under this study were formed by clustering the target areas using the criteria of climatological conditions such as geography, ocean, and land. Research is limited to tropics from 18 deg north to 18 deg south. A correlational study indicates that there is high positive correlation between high clouds and albedo, and a reduced negative correlation between albedo and net radiation.

Dhuria, Harbans L.↗
NASA NTRS1989

The cloud and surface contributions to the net radiation balance during the 1982-83 El Nino

This paper investigates the interannual fluctuations in cloud and surface forcing associated with the unusually intense ENSO event of 1982-1983. The analysis was performed over a six-year period for which global radiation budget and cloudiness measurements from the Nimbus-7 experiments were available simultaneously. It is shown that major anomalies in cloudiness, due mostly to shifts of a major convective center in the Pacific Ocean associated with inactive or active ENSO phase, are most notable over the equatorial central Pacific, the maritime continent over the western Pacific, the South Pacific convergence zone, and the Indian Ocean.

Sohn, Byung-Ju↗
NASA NTRS1972

Study to determine cloud motion from meteorological satellite data

Processing techniques were tested for deducing cloud motion vectors from overlapped portions of pairs of pictures made from meteorological satellites. This was accomplished by programming and testing techniques for estimating pattern motion by means of cross correlation analysis with emphasis placed upon identifying and reducing errors resulting from various factors. Techniques were then selected and incorporated into a cloud motion determination program which included a routine which would select and prepare sample array pairs from the preprocessed test data. The program was then subjected to limited testing with data samples selected from the Nimbus 4 THIR data provided by the 11.5 micron channel.

Clark, B. B.↗
NASA NTRS1990

SMM mesospheric ozone measurements

The main objective was to understand the secular and seasonal behavior of ozone in the lower mesosphere, 50 to 70 km. This altitude region is important in understanding the factors which determine ozone behavior. A secondary objective is the study of stratospheric ozone in the polar regions. Use is made of results from the SBUV satellite borne instrument. In the Arctic the interaction between chlorine compounds and low molecular weight hydrocarbons is studied. More than 30,000 profiles were obtained using the UVSP instrument on the SMM spacecraft. Several orbits of ozone data per day were obtained allowing study of the current rise in solar activity from the minimum until the present. Analysis of Nimbus 7 SBUV data in Antarctic spring indicates that ozone is depleted within the polar vortex relative to ozone outside the vortex. This depletion confirms the picture of ozone loss at altitudes where polar stratospheric clouds exist. In addition, there is ozone loss above the cloud level indicating that there is another mechanism in addition to ozone loss initiated by heterogeneous chlorine reactions on cloud particles.

Aikin, A. C.↗
NASA NTRS1975

A multisensor analysis of Nimbus-5 data recorded on 22 January 1973

The Nimbus 5 meteorological satellite has a full complement of radiation sensors. Data from these sensors were analyzed and intercompared for orbits 569 and 570. The electrically-scanning microwave radiometer (19.35-GHz region) delineated rain areas over the ocean off the U.S. east coast, in good agreement with radar imagery, and permitted the estimation of rainfall rates in this region. Residual ground water, from abnormal rainfall in the lower Mississippi Valley, was indicated under clear sky conditions by soil brightness temperature values in the Nimbus 5 electrically scanning microwave radiometer and U.S. Air Force Data Acquisition and Processing Program infrared data. The temperature-humidity infrared radiometer (6.7 micron and 11 micron) showed the height and spatial configuration of frontal clouds along the east coast and outlined the confluence of a polar jet stream with a broad subtropical jet stream along the U.S. Gulf Coast. Temperature profiles from three vertical temperature sounders are found to be in good agreement with related radiosonde ascents along orbit 569 from the subtropics to the Arctic Circle.

Allison, L. J.↗
NASA NTRS2009

Changes in Cloud and Aerosol Cover (1980-2006) from Reflectivity Time Series Using SeaWiFS, N7-TOMS, EP-TOMS, SBUV-2, and OMI Radiance Data

The amount of solar radiation reflected back to space or reaching the Earth's surface is primarily governed by the amount of cloud cover and, to a much lesser extent, by Rayleigh scatteri ng, aerosols, and various absorbing gases (e.g., O3, NO2, H2O). A useful measure of the effect of cloud plus aerosol cover is given by the amount that the 331 run Lambert Equivalent Reflectivity (LER) ofa scene exceeds the surfuce reflectivity for snow/ice-free scenes after Rayleigh scattering has been removed. Twenty-eight years of reflectivity data are available by overlapping data from several satellites: N7 (Nimbus 7, TOMS; 331 nm) from 1979 to 1992, SBUV-2 series (Solar Backscatter Ultraviolet, NOAA; 331 nm) 1985 to 2007, EP (Earth-Probe, TOMS; 331 nm) 1997 to 2006, SW (SeaWiFS; 412 nm) 1998 to 2006, and OMI (Ozone Measuring Instrument; 331 nm) 2004-2007. Only N7 and SW have a sufficiently long data record, Sun-synchronous orbits, and are adequately calibrated for long-term reflectivity trend estimation. Reflectivity data derived from these instruments and the SBUV-2 series are compared during the overlapping years. Key issues in determining long-term reflecti vity changes that have occurred during the N7 and SW operating periods are discussed. The largest reflectivity changes in the 412 nm SW LER and 331 nm EP LER are found to occur near the equator and are associated with a large EI Nino-Southern Oscillation event. Most other changes that have occurred are regional, such as the apparent cloud decrease over northern Europe since 1998. The fractional occurrence (fraction of days) of high reflectivity values over Hudson Bay, Canada (snow/ice and clouds) appears to have decreased when comparing reflectivity data from 1980 to 1992 to 1997-2006, suggesting shorter duration of ice in Hudson Bay since 1980.

Herman, J. R.↗
NASA NTRS1987

Volcanic eruption detection with TOMS

The Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) is designed for mapping of the atmospheric ozone distribution. Absorption by sulfur dioxide at the same ultraviolet spectral wavelengths makes it possible to observe and resolve the size of volcanic clouds. The sulfur dioxide absorption is discriminated from ozone and water clouds in the data processing by their spectral signatures. Thus, the sulfur dioxide can serve as a tracer which appears in volcanic eruption clouds because it is not present in other clouds. The detection limit with TOMS is close to the theoretical limit due to telemetry signal quantization of 1000 metric tons (5-sigma threshold) within the instrument field of view (50 by 50 km near the nadir). Requirements concerning the use of TOMS in detection of eruptions, geochemical cycles, and volcanic climatic effects are discussed.

Krueger, Arlin J.↗
NASA NTRS1989

Investigating ocean surface solar irradiance using Nimbus-7 Earth Radiation Budget data

A new estimation technique is introduced, using a surface solar irradiance database with advanced climate monitoring capabilities. Incorporating the Nimbus-7 Earth Radiation Budget (ERB) planetary albedo data obtained from wide-field-of-view radiometer measurements, the new solar irradiance model uses plane-parallel theory and assumes the isotropy of radiance reflected by the clouds and ocean surface. A brief description of the data, a treatment of the model verification, and a discussion of surface solar irradiance variability are presented. The results demonstrate the model's sensitivity to large-scale seasonal and interannual phenomena. A summary of the investigation is also presented, along with a perspective on potential uses and future development.

Chertock, Beth↗
NASA NTRS1993

Differentiating the role of land surface variability and cloudiness variability on global energy transport within the atmosphere and oceans

The following provides the final report on NASA IDP Project NAGW-1840 'Differentiating the Role of Land Surface Variability on Global Energy Transport within the Atmosphere and Oceans'. The project was designed to investigate the role of regional perturbations in the earth radiation budget on atmospheric and oceanic energy transports on an interannual basis. We proposed a modeling strategy based on an entropy extremum principle that could be used to separate the transports into oceanic and atmospheric components so as to better understand the effects of regional perturbations at the distinct atmospheric and oceanic time scales. The original focus was to consider the maintenance and year-to-year modulation of a large-scale, low-latitude North African-West Pacific Ocean net radiation dipole, which we had detected in the Nimbus 6 and 7 record of earth radiation budget measurements, and which necessitated significant cross-meridional energy transports to maintain global equilibrium. In addition, perturbations in the radiation balance term were to be partitioned into cloud-induced and surface-induced components to better understand the feedbacks between clouds and surface boundary conditions on interannual variability of the radiation balance.

Smith, Eric A.↗
NASA NTRS1992

Analysis of satellite-derived ozone and water vapor measurements

Research under this grant has involved analyses of satellite-derived measurements of water vapor and total ozone. Upper tropospheric water vapor data from the Nimbus 7 temperature-humidity infrared radiometer (THIR) 6.7 micron channel were analyzed by Fourier transformation to provide wavenumber spectra for a case of an upper level system over Europe. The power law spectrum for horizontal scales from 60 to several hundred km suggests that when convective cloud energy sources are not present, the enstrophy-cascading process (with variance proportional to the minus three power of wavenumber) may hold to much smaller scales than previously thought. Several investigations of the middle atmosphere (stratosphere and mesosphere) were also conducted. Slow atmospheric oscillations with periods of 1-2 months were investigated in total ozone measurements and in ionospheric data. Using one-point correlation maps and total ozone mapping spectrometer (TOMS) data, strong statistical evidence was found for the planetary-scale oscillations at these periods. A dipole-like pattern in the tropical equatorial Indian ocean-western Pacific region was documented, along with wavetrain-like patterns emanating into the extratropics. While attempting to follow the oscillations upward above stratosphere, oscillations were studied in ionospheric data (D-region radio wave absorption, in the upper mesosphere, around 80-90 km altitude). Cross-spectral analyses with solar flux data revealed that much of the observed 1-2 month variance in the ionospheric D-region was well correlated to solar variations. Further research has involved investigations of the photochemical lifetime of greenhouse gases methane and nitrous oxide. Using Nimbus 7 satellite data, a new analysis technique was employed to determine the lifetime of these gases in situ in the upper stratosphere. The lifetimes are found to be in good agreement with theoretical estimates.

Stanford, John L.↗
NASA NTRS1981

Raingage network sampling statistics

Sampling problems raise large difficulties for the precipitation measurements from space. In the tropics rainfall processes are organized in scales which are hardly resolved by the microwave radiometers on board of satellites. Even in the cloud clusters, which mark significant, large extended signals in the visible and infrared images, the precipitation areas cover only a small region. Our analysis of the cloud clusters over the W Pacific Ocean revealed that more than 50% of the area of a typical Western Pacific cluster are without rain. The radar observations during GATE generally confirmed those results. The rainfall was calculated from Nimbus V microwave data at 19.35 GHz and the results were compared with the GATE radar rainfall. The results are improved if the rain areas within the field of view are determined by additional observations and lead to a correction of the microwave brightness temperature.

Vogel, J. L.↗
NASA NTRS1988

An example of estimates of precipitable water derived from Nimbus-7 SMMR satellite measurements and FGGE upper air data

A sample of results from the Scanning Multichannel Microwave Radiometer (SMMR) instrument aboard the Nimbus-7 satellite is compared with those obtained from analyses of First GARP Global Experiment Level III-b data collected over the South Pacific on January 10-18, 1979, when the South Pacific Convergence Zone and its accompanying cloud band were quasi-stationary features of this ocean's circulation. It is found that the patterns of Goddard Laboratory for Atmospheres precipitable water values compare well with patterns of the SMMR brightness temperature differences.

Miller, Douglas K.↗
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.↗