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Lee, Robert B., III

Publications and source records attributed to Lee, Robert B., III.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Recent decreasing trend in the total solar irradiance - 1981-1992 spacecraft measurements

During 1990-1992, pyrheliometric measurements from the Earth Radiation Budget Satellite (ERBS) indicate that the total solar irradiance is decreasing at an annual rate of -0.2 Wm exp -2 with declining solar magnetic activity. Regression analyses of spacecraft irradiance measurements and of solar magnetic activity indices (10.7-cm solar radio flux and photometric sunspot index) verified the ERBS decreasing trend. The decreasing rate suggests that the irradiance should decrease 0.1 percent by 1997 when minimum solar magnetic activity is forecasted. If the forecasted 1990-1997 irradiance decrease is equal in magnitude to the magnitude of the 1986-1989 irradiance rise, one could conclude that solar irradiance variability has a strong 11-year component and no significant 22-year component. The ERBS measurements yielded 1365.4 +/- 0.7 Wm exp -2 as the mean irradiance value. In this paper, 1981-1992 spacecraft irradiance measurements are presented and compared with solar indices.

Lee, Robert B., III↗
NASA NTRS1992

Characterizations of the mirror attenuator mosaic - Solar diffuser plate

The mirror attenuator mosaic (MAM), a solar diffuser plate, was used for the flight calibration of the broadband shortwave (0.2-5-microns) and total (0.2 to greater than 200-microns) Earth Radiation Budget Experiment scanning thermistor bolometer radiometers. The MAM solar-reflecting surface consisted of a tightly packed array of vacuum-deposited aluminum, concave spherical mirrors, while its solar-absorbing surface consisted of black chrome. The effective reflectance of the MAM was constant to within +/- 2 percent after almost 2 years in orbit, a marked improvement over earlier solar diffusers.

Lee, Robert B., III↗
NASA NTRS1992

Correlation of solar irradiance and atmospheric temperature variations derived from spacecraft radiometry

Long-term changes in the mean global atmospheric temperature and the total solar irradiance were examined utilizing 1979-1989 spacecraft measurements. Outgoing longwave radiation at the top of the atmosphere was employed to infer global atmospheric temperatures. Evidence was determined that indicates the global temperatures should decline in the 1990-1997 period as the magnitude of the incoming solar irradiance declines with decreasing solar magnetic activity.

Lee, Robert B., III↗
NASA NTRS1992

Thermistor bolometer scanning radiometer - Applications and flight experience

Scanning radiometers aboard both high-altitude sun-synchronous polar orbit and low altitude equatorial orbit spacecraft have conducted measurements of the earth's long-wave radiation. Attention is presently given to the Earth Radiation Budget Satellite Experiment instruments, which are designed to measure earth radiance with an absolute radiometric error of less than 1 percent. The scanner instruments consists of three broadband radiometer channels employing thermistor bolometers as sensing elements; these radiometers repeatedly scan the earth from limb to limb every 4 sec, generating contiguous pixels on the earth's surface.

Kopia, Leonard P.↗
NASA NTRS1992

Evaluation of the Earth Radiation Budget Experiment (ERBE) shortwave channel's stability using in-flight calibration sources

The Earth Radiation Budget Experiment (ERBE) radiometers were designed to make absolute measurements of the incoming solar, earth-reflected solar, and earth-emitted fluxes for investigations of the earth's climate system. Thermistor bolometers were the sensors used for the ERBE scanning radiometric package. Each thermistor bolometer package consisted of three narrow field of view broadband radiometric channels measuring shortwave, longwave, and total (0.2 micron to 50 microns) radiation. The in-flight calibration facilities include Mirror Attenuator Mosaics, shortwave internal calibration source, and internal blackbody sources to monitor the long-term responsivity of the radiometers. This paper describes the in-flight calibration facilities, the calibration data reduction techniques, and the results from the in-flight shortwave channel calibrations. The results indicate that the ERBE shortwave detectors were stable to within +/- 1 percent for up to five years of flight operation.

Gibson, Michael A.↗
NASA NTRS1992

Implications of solar irradiance variability upon long-term changes in the Earth's atmospheric temperatures

From 1979 through 1987, it is believed that variability in the incoming solar energy played a significant role in changing the Earth's climate. Using high-precision spacecraft radiometric measurements, the incoming total solar irradiance (total amount of solar power per unit area) and the Earth's mean, global atmospheric temperatures were found to vary in phase with each other. The observed irradiance and temperature changes appeared to be correlated with the 11-year cycle of solar magnetic activity. During the period from 1979 through 1985, both the irradiance and temperature decreased. From 1985 to 1987, they increased. The irradiance changed approximately 0.1 percent, while the temperature varied as much as 0.6 C. During the 1979-1987 period, the temperatures were forecasted to rise linearly because of the anthropogenic build-up of carbon dioxide and the hypothesized 'global warming', 'greenhouse effect', scenarios. Contrary to these scenarios, the temperatures were found to vary in a periodic manner in phase with the solar irradiance changes. The observed correlations between irradiance and temperature variabilily suggest that the mean, global temperature of the Earth may decline between 1990 and 1997 as solar magnetic activity decreases.

Lee, Robert B., III↗
NASA NTRS1992

Flight solar calibrations using the Mirror Attenuator Mosaic (MAM): Low scattering mirror

Measurements of solar radiances reflected from the mirror attenuator mosaic (MAM) were used to calibrate the shortwave portions of the Earth Radiation Budget Experiment (ERBE) thermistor bolometer scanning radiometers. The MAM is basically a low scattering mirror which has been used to attenuate and reflect solar radiation into the fields of view for the broadband shortwave (0.2 to 5 micrometers) and total (0.2 to 50.0+ micrometers) ERBE scanning radiometers. The MAM assembly consists of a tightly packed array of aluminum, 0.3175-cm diameter concave spherical mirrors and field of view limiting baffles. The spherical mirrors are masked by a copper plate, electro-plated with black chrome. Perforations (0.14 centimeter in diameter) in the copper plate serve as apertures for the mirrors. Black anodized aluminum baffles limit the MAM clear field of view to 7.1 degrees. The MAM assemblies are located on the Earth Radiation Budget Satellite (ERBS) and on the National Oceanic and Atmospheric Administration NOAA-9 and NOAA-10 spacecraft. The 1984-1985 ERBS and 1985-1986 NOAA-9 solar calibration datasets are presented. Analyses of the calibrations indicate that the MAM exhibited no detectable degradation in its reflectance properties and that the gains of the shortwave scanners did not change. The stability of the shortwave radiometers indicates that the transmission of the Suprasil W1 filters did not degrade detectably when exposed to Earth/atmosphere-reflected solar radiation.

Lee, Robert B., III↗
NASA NTRS1992

Non-Scanning Radiometer Results for Earth Radiation Budget Investigations

The Earth Radiation Budget Experiment (ERBE) included non-scanning radiometers (Luther, 1986) flown aboard a dedicated mission of Earth Radiation Budget Satellite, and the NOAA-9 and -10 operational meteorological spacecraft (Barkstrom and Smith, 1986). The radiometers first began providing Earth radiation budget data in November 1984 and have remained operational, providing a record of nearly 8 years of data to date for researchers. Although they do not produce measurements with the resolution given by the scanning radiometers, the results from the non-scanning radiometers are extremely useful for climate research involving long-term radiation data sets. This paper discusses the non-scanning radiometers, their stability, the method of analyzing the data, and brief scientific results from the data.

Smith, G. Louis↗
NASA NTRS1991

A validation tool for the Earth Radiation Budget Experiment nonscanning radiometers

Two data sets for one geographical scene are used as a comparative validation tool to verify the quality of radiometer measurements taken for NASA's Earth Radiation Budget Experiment (ERBE). The measurements are taken from four independent nonscanning radiometers installed on the Earth Radiation Budget Satellite and two NOAA spacecraft. Two radiometers measure radiation in the 0.2-50-micron range, and two measure solar reflected energy in spectral band ranging from 0.2 to 5 microns. Calculated top-of-atmosphere flux-value measurements for day and night demonstrate significant correlation as well as consistency and stability over a three-year period. It is concluded that intercomparisons of intersections between the satellites are necessary over varied geographical scenes to utilize the subject method in validating the measurements of the ERBE nonscanning radiometer.

Bolden, William C.↗
NASA NTRS1991

Monitoring the earth's emission using nonscanning radiometric measurements of ERBS satellite

The outgoing longwave flux is determined using the data measured by two medium field-of-view (MFOV) nonscanning sensors employed on the Earth Radiation Budget Satellite (ERBS) spacecraft launched on October 5, 1984 in a nonsun-synchronous trajectory. The two MFOV sensors are MFOV-T that measures the radiation in the wavelength region of 0.2 to 50 microns and MFOV-SW that senses the reflected radiation in the spectral band of 0.2 to 5.0 microns. The outgoing longwave fluxes for MFOV at satellite altitude are determined by subtracting the shortwave fluxes from the total fluxes measured by MFOV-T channel. The Stefan-Boltzmann law is used to determine the outgoing long-wave fluxes at the top of the atmosphere and the equivalent atmospheric temperatures.

Pandey, Dhirendra K.↗
NASA NTRS1990

Long-term Solar Irradiance Variability: 1984-1989 Observations

Long-term variability in the total solar irradiance has been observed in the Earth Radiation Budget Experiment (ERBE) solar monitor measurements. The monitors have been used to measure the irradiance from the Earth Radiation Budget Satellite (ERBS) and the National Oceanic and Atmospheric Administration NOAA-9 and NOAA-10 spacecraft platforms since October 25, 1984, January 23, 1985, and October 22, 1986, respectively. Before September 1986, the ERBS irradiance values were found to be decreasing -0.03 percent per year. This period was marked by decreasing solar magnetic activity. Between September 1986 and mid-1989, the irradiance values increased approximately 0.1 percent. The latter period was marked by increasing solar activity which was associated with the initiations of the sunspot cycle number 22 and of a new 22-year Hale solar magnetic cycle. Therefore, long-term solar-irradiance variability appears to be correlated directly with solar activity. The maximum smoothed sunspot number occurred during September 1989, according to the Sunspot Index Data Center. Therefore, the recent irradiance increasing trend should disappear during early 1990 and change into a decreasing trend if the observed irradiance variability is correlated more so with the 11-year sunspot cycle than the 22-year Hale cycle. The ERBE irradiance values are presented and compared with sunspot activity for the 1984 to 1989 period. The ERBE values are compared with those available from the Nimbus-7 and Solar Maximum Mission spacecraft experiments.

Lee, Robert B., III↗
NASA NTRS1990

Solar Constant Data from Earth Radiation Budget Measurements

At present, solar total irradiance measurements are made from four satellites using electrically self calibrating pyrheliometers, as a part of the earth radiation budget measurement programs. The Earth Radiation Budget (ERB) mission onboard Nimbus-7 spacecraft (Nimbus/ERB) started solar total irradiance measurements in November 1978, and is still obtaining irradiance data on every orbit, daily. The Earth Radiation Budget Experiment (ERBE) solar monitors onboard Earth Radiation Budget Satellite (ERBS), NOAA-9 and NOAA-10 started solar total irradiance measurements in October 1984, January 1985, and October 1986, respectively. Our knowledge of solar total irradiance and its variability has grown remarkably during the past few years, as a result of the above measurements, and the high precision data obtained from Solar Maximum Mission/Active Cavity Radiometer Irradiance Monitor-1 (SMM/ACRIM-1). The results from a comparative study of the solar constant data available from the above missions are presented. The solar constant value derived from the sensors agree within the uncertainty associated with absolute pyrheliometers available at present. An attempt will be made to correlate the solar irradiance variability with other solar parameters. The measurements from Nimbus-7/ERB started November 1978, as the solar cycle 21 was increasing in activity. The solar luminosity reached a maximum in the spring of 1979. The irradiance then decreased slowly to a minimum which lasted from 1984 through 1986. The irradiance is presently increasing towards a new maximum. It appears that the solar constant value follow an eleven year cycle.

Mecherikunnel, A. T.↗
NASA NTRS1990

Earth Radiation Budget Experiment - Preliminary seasonal results

Over the previous four years the Earth Radiation Budget Experiment (ERBE) instruments have been gathering data on two satellites, the Earth Radiation Budget Satellite and the the operational NOAA-9 satellite. The ERBE science team recently completed the validation of an initial sampling of these data involving intensive examination of data in four months during 1985 and 1986. The data being placed in the National Space Science Data Center to acquaint the scientific community with their availability are discussed. The ERBE archival data products are also presented.

Barkstrom, Bruce R.↗
NASA NTRS1990

Earth Radiation Budget Experiment - Preliminary seasonal results

Data from the Earth Radiation Budget Satellite (ERBS) and from the operational NOAA-9 satellite being placed in the archive of the earth Radiation Budget Experiment (ERBE) are discussed. The results of the ERBE data validation effort are reviewed along with ERBE solar constant observations and earth-viewing results. The latter include monthly average results for July 1985, annual average clear-sky fluxes, and annual average, zonal, and global results.

Barkstrom, Bruce R.↗
NASA NTRS1990

Earth Radiation Budget Experiment (ERBE) scanner instrument

Orbital measurements of the earth's longwave emitted radiation, and the sun's radiation reflected by the earth are being made by scanning radiometers on three spacecraft platforms in both high altitude sun-synchronous polar (833 km) and low altitude (600 km) equatorial orbits. These ERBE instruments were carried aboard two TIROS ATN satellites (NOAA-9 and -10) in December 1984, and September 1986, and on the Earth Radiation Budget Satellite launched from Space Shuttle mission 41-G in October 1984. Electronic problems with the scanners on all platforms have halted the reception of data after surpassing the scanner design life. The ERBE instruments have been designed to measure the radiance from earth with an absolute radiometric error of less than one percent. The scanner instrument consists of three broadband radiometer channels, shortwave, 0.25 micron to 3.5 microns, longwave 5.0 to 50 microns; and total, 0.25 microns to more than 50 microns, and use thermistor bolometers as sensing elements. This paper describes the design and operation of the ERBE scanner, an overview of the ground calibration approach, the in-flight calibration stability, and an analysis of on-orbit anomalous behavior.

Kopia, Leonard P.↗
NASA NTRS1990

Earth Radiation Budget Experiment scanner radiometric calibration results

The Earth Radiation Budget Experiment (ERBE) scanning radiometers are producing measurements of the incoming solar, earth/atmosphere-reflected solar, and earth/atmosphere-emitted radiation fields with measurement precisions and absolute accuracies, approaching 1 percent. ERBE uses thermistor bolometers as the detection elements in the narrow-field-of-view scanning radiometers. The scanning radiometers can sense radiation in the shortwave, longwave, and total broadband spectral regions of 0.2 to 5.0, 5.0 to 50.0, and 0.2 to 50.0 micrometers, respectively. Detailed models of the radiometers' response functions were developed in order to design the most suitable calibration techniques. These models guided the design of in-flight calibration procedures as well as the development and characterization of a vacuum-calibration chamber and the blackbody source which provided the absolute basis upon which the total and longwave radiometers were characterized. The flight calibration instrumentation for the narror-field-of-view scanning radiometers is presented and evaluated.

Lee, Robert B., III↗
NASA NTRS1990

Ground and in-flight calibrations for the Earth Radiation Budget Experiment (ERBE) nonscanning radiometers

This paper describes the algorithms and procedures used for in-flight calibration of the nonscanning radiometers used in the Earth Radiation Budget Experiment (ERBE) instruments. The computation of the count conversion coefficients used in the basic ERBE radiometric equations is described, as well as the determination of the offsets and time-dependent coefficients used to account for the in-flight changes in the radiometers. The calibration results for more than 5 years of ERBE data are summarized for all nonscanning radiometers. Discontinuities in the observed data, and the effects of these discontinuities are discussed. Applications of ERBE type calibration algorithms to the EOS/CERES platforms are suggested.

Paden, Jack↗