Engineering topics

Hickey, J. R.

Publications and source records attributed to Hickey, J. R..

At least 19 records

NASA NTRS1994

A review of the Nimbus-7 ERB solar dataset

Fourteen years (November 16, 1978 through January 24, 1993) of Nimbus-7 total solar irradiance measurements have been made. The measured mean annual solar energy just outside of the Earth's atmosphere was about 0.1% (1.4 W per sq m) higher in the peak years of 1979 (cycle 21) and 1991 (cycle 22) than in the quiet Sun years of 1985/86. Comparison with shorter independent solar measurement sets and with empirical models qualitatively confirms the Nimbus-7 results. But these comparisons also raise questions of detail for future studies: in which years did the peaks actually occur and just how accurate are the models and the measurements?

Kyle, H. L.↗

NASA NTRS1991

Solar irradiance variability from modern measurements

Direct measurements from satellites of the solar 'constant' (the total irradiance at mean sun-earth distance) during more than ten years show variations over time scales from minutes to years and decades. At high frequencies, solar oscillations contribute to the variance. The most important influences are related to solar activity: during the passage of active regions on the solar disk (sunspots and faculae) changes of a few 0.1 percent lasting for several days are observed. The effects of spots can be well reproduced by the projected sunspot index, whereas the influence of faculae have to be modeled from proxy data like the Ca-K plage index or the He I index. Long-term trends are detected which are connected to the 11-yr solar activity cycle.

Froehlich, C.↗

NASA NTRS1988

Observation of total irradiance variability from Nimbus satellites

The cavity pyrheliometer sensor aboard Nimbus 7 is now in its tenth year of operation. Results for 9 1/2 years show a decreasing trend through the end of solar cycle 21 of approximately -0.015 percent per year, a leveling off near solar minimum and an increasing irradiance for the beginning of cycle 22. Through April 1988, the irradiance has increased about 0.06 percent above the minimum value which was about 0.08 percent below the highest values obtained near solar maximum. The rise appears more rapid than the decline.

Hickey, J. R.↗

NASA NTRS1986

ERB Nimbus 7 solar measurements - 7 years

A discussion is presented of features of the nearly 7 yr of solar radiation data available from Nimbus-7 Earth Radiation Budget (ERB) experiments as of early 1986. Summaries are provided of the irradiance data collected by each of the 10 solar sensors, with account taken of the degradation of sensor sensitivity over the active life of the sensors. In contrast, however, has been the performance of the cavity pyrheliometer, channel 10C, which has maintained an accuracy of 0.05 percent after over 6 yr on-orbit. As has been observed in SMM data, the total daily solar irradiance has exhibited a downward trend over the lifetimes of both instruments.

Hickey, J. R.↗

NASA NTRS1984

User's guide for the Nimbus 7 ERB Solar Analysis Tape (ESAT)

Five years of Nimbus 7 ERB solar data is available in compact form on a single ERB solar analysis tape (ESAT). The period covered is November 16, 1978 through October 31, 1983. The Nimbus 7 satellite performs just under 14 orbits a day and the ERB solar telescope observe the Sun once per orbit as the satellite passes + or - near the south pole. The data were carefully calibrated and screened. Mean orbital and daily values are given for the total solar irradiance plus selected spectral intervals. In addition, selected solar activity indicators are on the tape. The ERB experiment, the solar data calibration and screening procedures, the solar activity indicators, and the tape format are described briefly.

Hickey, J. R.↗

NASA NTRS1984

The earth radiation budget derived from the Nimbus 7 ERB experiment

The earth radiation budget as determined from the ERB experiment aboard the Nimbus-7 polar-orbiting satellite is presented in the form of time-latitude cross sections, hemispherically and globally averaged time plots, and annual global averages for the time period spanning November 1978 through October 1979. Comparisons are made between results derived from the fixed wide-field-of-view (WFOV) radiometers and those derived from the scanning narrow-field-of-view (NFOV) radiometers. While there is excellent agreement in regard to the spatial and temporal variations, the absolute magnitudes differ. The NFOV yields outgoing longwave fluxes and albedos that are about 4W/sq m and 2.5 percent, respectively, greater than those derived from the WFOV sensors. Also, limited simultaneous comparisons are made between ERB results and those from the AVHRR on the NOAA-7 operational satellite.

Jacobowitz, H.↗

NASA NTRS1984

New in-flight calibration adjustment of the Nimbus 6 and 7 earth radiation budget wide field of view radiometers

In-flight calibration adjustments are developed to process data obtained from the wide-field-of-view channels of Nimbus-6 and Nimbus-7 after the failure of the Nimbus-7 longwave scanner on June 22, 1980. The sensor characteristics are investigated; the satellite environment is examined in detail; and algorithms are constructed to correct for long-term sensor-response changes, on/off-cycle thermal transients, and filter-dome absorption of longwave radiation. Data and results are presented in graphs and tables, including comparisons of the old and new algorithms.

Kyle, H. L.↗

NASA NTRS1984

Status of Solar Measurements and Data Reduction for Erb-nimbus 7

The status of the Total Solar Irradiance data obtained using the cavity radiometer aboard the Earth Radiation Budget experiment of the Nimbus 7 satellite is described. The ERB experiment has a number of sensors which measure the radiative fluxes (both shortwave and infrared) leaving the Earth as well as the solar channels. The complexity of the processing of the Earth-flux data, both wide and narrow angle has necessitated a reprocessing effort which produces the final data. Since the solar data is embedded in the same data stream and tape product as the Earth-flux data, it was not generally available in a format convenient for analysis as a separate product. Values for the final data product only are presented and a few remarks concerning the basic features of the data. There is no scientific conclusions presented here other than those directly related to the measurement results. A set of tabulated values is appended.

Hickey, J. R.↗

NASA NTRS1984

Passive exposure of Earth radiation budget experiment components (A0147)

In-flight calibration for the solr and Earth flux channels was examined. Earth Radiation on Budget (ERB) channel components were exposed to the space environment and then retrieved and resubmitted to radiometric calibration after exposure. It is suggested that corrections may be applied to ERB results and information will be obtained to aid in the selection of components for future operational solar and Earth radiation budget experiments. To assure that these high accuracy devices are measuring real variations and are not responding to changes induced by the space environment, it is desirable to test such devices radiometrically after exposure to the best approximation of the orbital environment.

Hickey, J. R.↗

NASA NTRS1983

Exospheric cleaning of the Earth Radiation Budget solar radiometer during solar maximum

Anomalous behavior of the Earth Sensor Assemblies (ESA) had been observed on the Defense Meteorological Satellite Program (DMSP) 5D/1 satellites and the Tiros-N satellite. The present investigation is concerned with the reasons for the observed phenomena. Degradation of the Earth Radiation Budget (ERB) solar channels and the Solar Backscatter Ultraviolet and Total Ozone Mapping Spectrometer (SBUV/TOMS) diffuser plate is attributed to transmission or reflection loss originating from the growth of an organic film by photolytic polymerization. Simultaneous degradation of the ESA interference filter coated lenses facing the flight direction and the recovery of the ERB solar channels on Nimbus 6 and 7 is caused by a reaction with the increase in the exospheric atmospheric density caused by solar maximum.

Predmore, R. E.↗

NASA NTRS1983

The nature of the short period fluctuations in solar irradiance received by the earth

An analysis of the periodicities found in the Nimbus-7 satellite measurements of solar irradiance (Solar Constant) indicates variations on three scales. Two of these variations are shown to be related to variations in solar activity as given by various indicators of solar photosphere disturbances. The high frequency periodicity is due to the solar rotation period. The second periodicity is based on the integral effect of the high frequency oscillation over an 11 year solar cycle. The third variation (secular trend) is discussed in regard to the high precision cavity data and the recent record of high altitude solar constant measurements.

Smith, E. A.↗

NASA NTRS1983

The spectral nature of solar irradiance variability and its phase relationship to solar activity

Rather firm conclusions regarding the nature of short term solar variability have been reached on the basis of recent studies of continuous time series of solar irradiance measurements. The measurements have been conducted with the aid of satellite mounted cavity radiometers. The present paper provides an interim report on further analysis concerning the spectral nature of solar variation and its relationship to other indicators of solar variability. It is pointed out that the Nimbus 7-ERB mission was able to deliver rather precise and continuous measures of solar irradiance at a variety of spectral bands. Spectral variations observed in the Nimbus 7-ERB solar monitor measurements appear to correspond to a quasi-black body shift due to the appearance of large earth-facing sun spots.

Smith, E. A.↗

NASA NTRS1982

Latest rocket measurements of the solar constant

Three rocket flights which carried a payload of absolute radiometers to measure the solar constant with an accuracy of plus or minus 0.5 per cent have been accomplished. Several of the rocket radiometers were duplicates of those aboard the Solar Maximum Mission and Nimbus spacecrafts. The values for the solar constant obtained by the rocket sensors for the three flight dates indicate an increase between the first and latter two flights approximately equivalent to the uncertainty of the measurements. The values for the solar constant for the three flights are 1367, 1372 and 1374 W/sq m.

Duncan, C. H.↗

NASA NTRS1982

Experimental evaluation of self-calibrating cavity radiometers for use in earth flux radiation balance measurements from satellites

A method for evaluating out-of-field response of wide-field, earth-viewing satellite radiometers is described. The equipment which simulates the earth and space consists of a central blackbody surrounded by a cooled ring. The radiometric and orbital considerations are discussed. Some test results for prototype ERBE cavity sensors are included. This presentation is restricted to longwave radiative transfer

Hickey, J. R.↗

NASA NTRS1981

Solar variability indications from Nimbus 7 satellite data

The cavity pyrheliometer sensor of the Nimbus 7 Earth Radiation Experiment indicated low-level variability of the total solar irradiance. The variability appears to be inversely correlated with common solar activity indicators in an event sense. the limitations of the measuring system and available data sets are described.

Hickey, J. R.↗

NASA NTRS1978

The Earth Radiation Budget (ERB) experiment

The radiation budget of the earth on both synoptic and planetary scales by simultaneous measurement of incoming solar radiation and outgoing earth reflected (shortwave) and emitted (longwave) radiation was determined. Both fixed wide angle sampling of terrestrial fluxes at the satellite altitude, and scanned narrow-angle sampling of the radiance components, dependent on angle are used to determine outgoing radiation. Measurements of radiation are obtained in 22 different optical channels.

Jacobowitz, H.↗

NASA NTRS1977

Rocket calibration of the Nimbus 6 solar constant measurements

A sounding rocket experiment was performed in June 1976, in which the solar constant was observed simultaneously outside the earth's atmosphere by three types of absolute cavity radiometers (the Primary Absolute Cavity Radiometer and two Active Cavity Radiometers, Type IV) and duplicates of Nimbus 6 ERB/ESP (Earth Radiation Budget/Eclectic Satellite Pyrheliometer) solar channels. The preliminary average solar constant result from the cavity radiometers is 1367 W/sq m with an uncertainty of less than plus or minus 0.5% in SI units. The duplicate ERB channel 3 on the rocket gave a value of 1389 W/sq m, which agreed exactly with the Nimbus 6 ERB channel 3 measurement made simultaneously with the rocket flight.

Duncan, C. H.↗

NASA NTRS1977

Rocket calibration of the Nimbus 6 solar constant measurements

Total solar irradiance was observed simultaneously outside the earth's atmosphere by three types of absolute cavity radiometers and duplicates of four of the Nimbus 6 Earth Radiation Budget (ERB) solar channels in a June 1976 sounding rocket experiment. The preliminary average solar constant result from the cavity radiometers is 1367 Wm (-2) with an uncertainty of less than + or - 0.5% in S.I. units. The duplicate ERB channel 3 on the rocket gave a value of 1389 Wm (-2) which agreed exactly with the Nimbus 6 ERB channel 3 measurement made simultaneously with the rocket flight.

Duncan, C. H.↗