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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 NTRS2002

Radiometric Characterization of IKONOS Multispectral Imagery

A radiometric characterization of Space Imaging's IKONOS 4-m multispectral imagery has been performed by a NASA funded team from the John C. Stennis Space Center (SSC), the University of Arizona Remote Sensing Group (UARSG), and South Dakota State University (SDSU). Both intrinsic radiometry and the effects of Space Imaging processing on radiometry were investigated. Relative radiometry was examined with uniform Antarctic and Saharan sites. Absolute radiometric calibration was performed using reflectance-based vicarious calibration methods on several uniform sites imaged by IKONOS, coincident with ground-based surface and atmospheric measurements. Ground-based data and the IKONOS spectral response function served as input to radiative transfer codes to generate a Top-of-Atmosphere radiance estimate. Calibration coefficients derived from each vicarious calibration were combined to generate an IKONOS radiometric gain coefficient for each multispectral band assuming a linear response over the full dynamic range of the instrument. These calibration coefficients were made available to Space Imaging, which subsequently adopted them by updating its initial set of calibration coefficients. IKONOS imagery procured through the NASA Scientific Data Purchase program is processed with or without a Modulation Transfer Function Compensation kernel. The radiometric effects of this kernel on various scene types was also investigated. All imagery characterized was procured through the NASA Scientific Data Purchase program.

Pagnutti, Mary↗

NASA NTRS1977

Calibration analysis for a multi-channel infrared scanning radiometer

A procedure for calibrating an infrared scanning spectroradiometer by a computerized parametric error analysis technique was developed. The uncertainties in the radiometric measurements of scene radiance and (for the case of a blackbody scene) temperature due to possible uncertainties in the calibration target temperature, calibration target emissivity, and instrument temperature were calculated for a range of uncertainty levels in the parameters, as well as for a gamut of scent temperatures corresponding to a given spectral channel. This technique is applicable to the radiometric calibration of any infrared radiometer. It was applied specifically to the Cloud-Top Scanning (C.T.S) Radiometer, a three-channel instrument designed for aircraftborne cloud radiance measurements in the 6.75 and 11.5 micron thermal emission spectral regions.

Walden, H.↗

NASA NTRS2010

Simplified Vicarious Radiometric Calibration

A measurement-based radiance estimation approach for vicarious radiometric calibration of spaceborne multispectral remote sensing systems has been developed. This simplified process eliminates the use of radiative transfer codes and reduces the number of atmospheric assumptions required to perform sensor calibrations. Like prior approaches, the simplified method involves the collection of ground truth data coincident with the overpass of the remote sensing system being calibrated, but this approach differs from the prior techniques in both the nature of the data collected and the manner in which the data are processed. In traditional vicarious radiometric calibration, ground truth data are gathered using ground-viewing spectroradiometers and one or more sun photometer( s), among other instruments, located at a ground target area. The measured data from the ground-based instruments are used in radiative transfer models to estimate the top-of-atmosphere (TOA) target radiances at the time of satellite overpass. These TOA radiances are compared with the satellite sensor readings to radiometrically calibrate the sensor. Traditional vicarious radiometric calibration methods require that an atmospheric model be defined such that the ground-based observations of solar transmission and diffuse-to-global ratios are in close agreement with the radiative transfer code estimation of these parameters. This process is labor-intensive and complex, and can be prone to errors. The errors can be compounded because of approximations in the model and inaccurate assumptions about the radiative coupling between the atmosphere and the terrain. The errors can increase the uncertainty of the TOA radiance estimates used to perform the radiometric calibration. In comparison, the simplified approach does not use atmospheric radiative transfer models and involves fewer assumptions concerning the radiative transfer properties of the atmosphere. This new technique uses two neighboring uniform ground target areas having different reflectance values. The target areas can be natural or artificial and must be large enough to minimize adjacent-pixel contamination effects. The radiative coupling between the atmosphere and the terrain needs to be approximately the same for the two targets. This condition can be met for relatively uniform backgrounds when the distance between the targets is within a few hundred meters. For each target area, the radiance leaving the ground in the direction of the satellite is measured with a radiometrically calibrated spectroradiometer. Using the radiance measurements from the two targets, atmospheric adjacency and atmospheric scattering effects can be subtracted, thereby eliminating many assumptions about the atmosphere and the radiative interaction between the atmosphere and the terrain. In addition, the radiometrically calibrated spectroradiometer can be used with a known reflectance target to estimate atmospheric transmission and diffuse- to-global ratios without the need for ancillary sun photometers. Several comparisons between the simplified method and traditional techniques were found to agree within a few percent. Hence, the simplified method reduces the overall complexity of performing vicarious calibrations and can serve as a method for validating traditional radiative transfer models

Stanley, Thomas↗

NASA NTRS2001

On-Orbit Performance of MODIS On-Board Calibrators

The Terra MODIS (Moderate Resolution Imaging Spectroradiometer) was launched on December 18, 1999 and acquired the first scene data on February 24, 2000. It has 36 spectral bands covering spectral range from 0.41 to 14.2 microns and provides spatial resolutions of 250 (2 bands), 500 (5 bands), and 1000 m at Nadir. The instrument on-orbit calibration and characterization are determined and monitored through the use of a number of on-board calibrators (OBC). Radiometric calibration for the reflective solar bands (B1-B19, B26), from VIS (visible) to SWIR (short wavelength infrared) (0.41 to 2.1 microns), uses a Spectralon (tm) solar diffuser (SD) and a solar diffuser stability monitor (SDSM). For the thermal emissive bands (B20-B25, B27-B36), from MWIR (medium wavelength infrared) to LWIR (long wavelength infrared) (3.75 to 14.2 micron), a V-grooved flat panel blackbody is used. The instrument spectral for the VIS to SWIR bands and spatial co-registration characterizations for all bands are monitored on-orbit by the spectral radiometric calibration assembly (SRCA). In this report, we discuss the application and performance of the key MODIS on-board calibrators and their impacts on the instrument system calibration and characterization.

Xiong, X.↗

NASA NTRS1973

Tracking and data system support for the Pioneer project. Volume 1: Pioneer 10-prelaunch planning through second trajectory correction, 4 December 1969 - 1 April 1972

The tracking and data system support of the launch, near-earth, and deep space phases of the Pioneer 10 mission, which sent a Pioneer spacecraft into a flyby of Jupiter that would eventually allow the spacecraft to escape the solar system is discussed. The support through the spacecraft's second trajectory correction is reported. During this period, scientific instruments aboard the spacecraft registered information relative to interplanetary particles and fields, and radiometric data generated by the network continued to improve knowledge of the celestial mechanics of the solar system. In addition to network support activity detail, network performance and special support activities are covered.

Siegmeth, A. J.↗

NASA NTRS1975

Spectroradiometric calibration techniques in the far ultraviolet - A stable emission source for the Lyman bands of molecular hydrogen

The problems associated with making accurate spectroradiometric measurements in the far UV region are sketched briefly. The equipment and methods that were developed for providing absolute sensitivity calibration of an Apollo 17 far UV spectrometer are described. The absolute reference standards were photoelectric diodes calibrated at the National Bureau of Standards. A complete vacuum optical facility, which included a premonochromator and stable UV light sources, was developed to calibrate the Apollo 17 instrument, and it has been used for a number of other tasks. Absolute radiometric calibrations between about 1200 and 1700 A were performed with an absolute accuracy of + or - 10%. The light source, which was designed to provide a very stable light output, is a low-pressure molecular hydrogen lamp in which the pressure is stabilized by thermal control of uranium hydride powder.-

Fastie, W. G.↗

NASA NTRS1987

Spectral and radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer

The laboratory spectral and radiometric calibration of the AVIRIS science data collected since 1987 is described. The instrumentation and procedures used in the calibration are discussed and the accuracy achieved in the laboratory as determined by measurement and calculation is compared with the requirements. Instrument performance factors affecting radiometry are described. The paper concludes with a discussion of future plans.

Vane, Gregg↗

NASA NTRS1988

Spectral and radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer

Vane, Gregg↗

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↗

NASA NTRS2010

NASA's Advancements in Space-Based Spectrometry Lead to Improvements in Weather Prediction and Understanding of Climate Processes

AIRS (Atmospheric Infra-Red Sounder), was launched, in conjunction with AMSU-A (Advanced Microwave Sounding Unit-A) on the NASA polar orbiting research satellite EOS (Earth Observing System) Aqua satellite in May 2002 as a next generation atmospheric sounding system. Atmospheric sounders provide information primarily about the vertical distribution of atmospheric temperature and water vapor distribution. This is achieved by measuring outgoing radiation in discrete channels (spectral intervals) which are sensitive primarily to variations of these geophysical parameters. The primary objectives of AIRS/AMSU were to utilize such information in order to improve the skill of numerical weather prediction as well as to measure climate variability and trends. AIRS is a multi-detector array grating spectrometer with 2378 channels covering the spectral range 650/cm (15 microns) to 2660/cm (3.6 microns) with a resolving power (i/a i) of roughly 1200 where a i is the spectral channel bandpass. Atmospheric temperature profile can be determined from channel observations taken within the 15 micron (the long-wave CO2 absorption band) and within the 4.2 micron (the short-wave CO2 absorption band). Radiances in these (and all other) spectral intervals in the infrared are also sensitive to the presence of clouds in the instrument?s field of view (FOV), which are present about 95% of the time. AIRS was designed so as to allow for the ability to produce accurate Quality Controlled atmospheric soundings under most cloud conditions. This was achieved by having 1) extremely low channel noise values in the shortwave portion of the spectrum and 2) a very flat spatial response function within a channel?s FOV. IASI, the high spectral resolution IR interferometer flying on the European METOP satellite, does not contain either of these important characteristics. The AIRS instrument was also designed to be extremely stabile with regard to its spectral radiometric characteristics, which is critical with regard to the ability to measure accurate long term trends.

Susskind, Joel↗

NASA NTRS2016

Demonstrating the Error Budget for the Climate Absolute Radiance and Refractivity Observatory Through Solar Irradiance Measurements

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a test-bed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO's climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

CLARREO↗

NASA NTRS2014

GMI Instrument Spin Balance Method, Optimization, Calibration, and Test

The Global Microwave Imager (GMI) instrument must spin at a constant rate of 32 rpm continuously for the 3 year mission life. Therefore, GMI must be very precisely balanced about the spin axis and CG to maintain stable scan pointing and to minimize disturbances imparted to the spacecraft and attitude control on-orbit. The GMI instrument is part of the core Global Precipitation Measurement (GPM) spacecraft and is used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and frequent precipitation measurements. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard Space Flight Center to design, build, and test the GMI instrument. The GMI design has to meet a challenging set of spin balance requirements and had to be brought into simultaneous static and dynamic spin balance after the entire instrument was already assembled and before environmental tests began. The focus of this contribution is on the analytical and test activities undertaken to meet the challenging spin balance requirements of the GMI instrument. The novel process of measuring the residual static and dynamic imbalances with a very high level of accuracy and precision is presented together with the prediction of the optimal balance masses and their locations.

Ayari, Laoucet↗

NASA NTRS2014

GMI Instrument Spin Balance Method, Optimization, Calibration and Test

The Global Microwave Imager (GMI) instrument must spin at a constant rate of 32 rpm continuously for the 3-year mission life. Therefore, GMI must be very precisely balanced about the spin axis and center of gravity (CG) to maintain stable scan pointing and to minimize disturbances imparted to the spacecraft and attitude control on-orbit. The GMI instrument is part of the core Global Precipitation Measurement (GPM) spacecraft and is used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and frequent precipitation measurements. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard Space Flight Center to design, build, and test the GMI instrument. The GMI design has to meet a challenging set of spin balance requirements and had to be brought into simultaneous static and dynamic spin balance after the entire instrument was already assembled and before environmental tests began. The focus of this contribution is on the analytical and test activities undertaken to meet the challenging spin balance requirements of the GMI instrument. The novel process of measuring the residual static and dynamic imbalances with a very high level of accuracy and precision is presented together with the prediction of the optimal balance masses and their locations.

Ayari, Laoucet↗

NASA NTRS1972

Airborne microwave radiometric data analysis

Results from the 1.5 cm, 19.35 GHz electrical scanning microwave radiometer which was once of the instruments used during the 1971 flight over Imperial Valley, California; Phoenix, Arizona; and Weslaco, Texas.

Source record↗

NASA NTRS1980

Feasibility of modifying the high resolution infrared radiation sounder (HIRS/2) for measuring spectral components of Earth radiation budget

The concept of adding four spectral channels to the 20 channel HIRS/2 instrument for the purpose of determining the origin and profile of radiant existence from the Earth's atmosphere is considered. Methods of addition of three channels at 0.5, 1.0 and 1.6 micron m to the present 0.7 micron m visible channel and an 18-25 micron m channel to the present 19 channels spaced from 3.7 micron m to 15 micron m are addressed. Optical components and physical positions were found that permit inclusion of these added channels with negligible effect on the performance of the present 20 channels. Data format changes permit inclusion of the ERB data in the 288 bits allocated to HIRS for each scan element. A lamp and collimating optic assembly may replace one of the on board radiometric black bodies to provide a reference source for the albedo channels. Some increase in instrument dimensions, weight and power will be required to accommodate the modifications.

Koenig, E. W.↗

NASA NTRS2020

SNPP VIIRS RSB on-orbit radiometric calibration algorithms Version 2.0 and the performances. Part II: The performances

In Part I (Lei et. al, submitted to J. of Appl. Rem. Sens.),we gave detailed reviews of the algorithms Version 2.0 used for the on-orbit radiometric calibration of the reflective solar bands (RSBs) of the first Visible Infrared Imaging Radiometer Suite instrument. These algorithms improve the accuracy of the measured on-orbit change factor of the solar diffuser bidirectional reflectance distribution function, the H-factor, and reveal that the H-factor is angle dependent. With the help of lunar observations and the improved H-factor, the algorithms give more accurate values for the RSB detector on-orbit F-factor changes (F-factor is a correction factor to the initially retrieved scene spectral radiance). In this paper we review the RSB radiometric calibration performances. We show the H-factor temporal trend, the estimated uncertainty of the retrieved H-factor, and the F-factor temporal trend. Additionally we show the detector signal-to-noise ratio (SNR), the estimated uncertainty of the top-of-the-atmosphere solar spectral reflectance, the reflectance temporal trend for the Libya 4 desert, and the differences in the reflectances among the SNPP and the NOAA-20 VIIRS, and the Aqua MODIS. Our results show that although the SNRs trend downwards, they exceed the requirements by large margins. The reflectances from the Libya 4 desert show that the SNPP VIIRS’ reflectance is higher than those of the Aqua MODIS and the NOAA-20 VIIRS.

on-orbit calibration↗

NASA NTRS2020

SNPP VIIRS RSB on-orbit radiometric calibration algorithms Version 2.0 and the performances. Part II: The performances

Ning Lei↗

NASA NTRSDate not supplied

Using DSCOVR EPIC as an Additional Calibration Reference to Radiometrically Scale the Geo Imagers for the NASA CERES Project

The NASA CERES project provides climate-quality observed TOA and calculated surface fluxes to the climate community. The CERES instruments are mounted on the Aqua, Terra, NPP, and NOAA-20 low earth orbiting (LEO) satellites, where they are used alongside the VIIRS and MODIS based cloud properties necessary for converting CERES radiance observations into fluxes. The CERES SYN1deg product provides the regional hourly fluxes in between the Terra and Aqua/NOAA-20-CERES observations based on geostationary imager (GEO) radiances. The GEO radiances are radiometrically scaled to the MODIS or VIIRS calibration references. The GEO and MODIS inter-calibration events are limited by the Aqua-MODIS or VIIRS local equator crossing time of 1:30 PM. The DSCOVR satellite orbits the Lagrange-1 (L1) point about 1.5 million kilometers from Earth, and the Earth Polychromatic Imaging Camera (EPIC) instrument onboard DSCOVR has a constant view of the sunlit side of the Earth while taking images ranging from the UV to the NIR throughout the day. While the EPIC sensor has no onboard calibration systems, multiple inter-calibration studies have indicated that EPIC is radiometrically stable, which allows it to potentially be used as a transfer radiometer between imagers. This study will assess the viability of using EPIC as a consistent and stable calibration source for GEO imagers. EPIC will be inter-calibrated with Himawari-8 that has been radiometrically scaled with Aqua. The Himawari-8 based EPIC calibration gains will be verified by the EPIC calibration gains determined directly from Aqua-MODIS matches. The EPIC calibration gains based on Himawari-8 will be stratified by local time to determine any diurnal dependence of the GEO/EPIC calibration strategy.

C O Haney↗