Search NASA⌕ Search

SEARCH · Search NASA

Results for “DNB”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

60 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

JPSS-2 VIIRS Pre-Launch Reflective Solar Band Testing and Performance

The Visible Infrared Imaging Radiometer Suite (VIIRS) instruments on-board the Suomi National Polar-orbiting Partnership (S-NPP) and Joint Polar Satellite System (JPSS) spacecrafts 1 and 2 provides calibrated sensor data record (SDR) reflectance, radiance, and brightness temperatures for use in environment data record (EDR) products. The SDRs and EDRs are used in weather forecasting models, weather imagery and climate applications such as ocean color, sea surface temperature and active fires. The VIIRS has 22 bands covering a spectral range 0.4–12.4 m with resolutions of 375 m and 750 m for imaging and moderate bands respectively on four focal planes. The bands are stratified into three different types based on the source of energy sensed by the bands. The reflective solar bands (RSBs) detect sunlight reflected from the Earth, thermal emissive bands (TEBs) sense emitted energy from the Earth and the day/night band (DNB) detects both solar and lunar reflected energy from the Earth. The SDR calibration uses a combination of pre-launch testing and the solar diffuser (SD), on-board calibrator blackbody (OBCBB) and space view (SV) on-orbit calibrator sources. The pre-launch testing transfers the National Institute of Standards and Technology (NIST) traceable calibration to the SD, for the RSB, and the OBCBB, for the TEB. Post-launch, the on-board calibrators track the changes in instrument response and adjust the SDR product as necessary to maintain the calibration. This paper will discuss the pre-launch radiometric calibration portion of the SDR calibration for the RSBs that includes the dynamic range, detector noise, calibration coefficients and radiometric uncertainties for JPSS-2 VIIRS.

JPSS↗
NASA NTRS2023

JPSS-3 VIIRS Version 2 at-Launch Relative Spectral Response Characterization

The JPSS-3 VIIRS sensor has completed its pre-launch test program including measurements for characterizing the VIIRS relative spectral response (RSR) in support of the Sensor and Environmental Data Records (SDR and EDR, resp.) that will be generated from VIIRS on-orbit observations. Government team subject matter experts of the VIIRS DAWG have analyzed the VIIRS spectral measurements and produced the VIIRS spectral characterization, in the form of band-average and supporting detector level RSR for each VIIRS band. The characterization is based upon the analysis of independent SpMA dual monochromator (all bands) and GSFC GLAMR laser system (reflectance bands only) spectral measurements. The SpMA and GLAMR measurements for reflectance bands (DNB LGS and MGS, I1-I3, M1-M11) were combined to produce a “fused” RSR. For emissive bands (I4, I5, M12-M16), the SpMA measurements provide the characterization. The effort has led to the VIIRS Version 2 RSR release, the official at-launch RSR characterization for the JPSS-3 VIIRS mission. The JPSS-3 RSR are a close match to those of JPSS-2. An assessment on compliance with spectral performance metrics finds that VIIRS band-average RSR are compliant on nearly all metrics, with only a single minor exception. The Version 2 RSR release is available under EAR99 restrictions to the science community on the restricted access NASA Sharepoint.

Chris Moeller↗
NASA NTRS2016

Characterization of Nighttime Light Variability Over the Southeastern United States

City lights provide indications of human activity at night. Nighttime satellite imagery offers daily snapshots of this activity. With calibrated, science-quality imagery, long-term monitoring can also be achieved. The degree to which city lights fluctuate, however, is not well known. For the application of detecting power outages, this degree of variability is crucial for assessing reductions to city lights based on historical trends. Eight southeastern U.S. cities are analyzed to understand the relationship between emission variability and several population centers. A preliminary, example case power outage study is also discussed as a transition into future work.

VIIRS↗
NASA NTRS2018

Performance Assessments and Comparisons of S-NPP and NOAA-20 (JPSS-1) VIIRS On-Orbit Calibration

The first Visible Infrared Imaging Radiometer Suite (VIIRS) instrument has been in operation for more than 6 years on-board the S-NPP satellite and the second instrument, with the same design and performance requirements, was launched in November, 2017 on-board the JPSS-1 satellite (named NOAA-20 after reaching its orbit) and is currently in normal operation conditions. This paper provides a brief description of VIIRS on-orbit calibration and characterization activities and presents performance assessments and comparisons of S-NPP and NOAA-20 VIIRS using data collected from their on-board calibrators (OBC) and regularly scheduled lunar observations. Results show that NOAA-20 VIIRS is performing as well or better than S-NPP VIIRS in all of the key performance metrics. The NOAA-20 reflective solar bands, including the day-night band, have experienced less than 1% change in gain in the first 250 days since launch and did not suffer from the contamination related rapid degradation experienced by S-NPP VIIRS. Some of the NOAA20 thermal emissive bands had larger than expected gain degradation after launch due to ice buildup on the dewar window of the long-wave IR focal plane assembly but a mid-mission outgassing operation was able to restore their gains and maintain stable behavior. Though this study is focused on the sensor's key performance parameters, such as detector responses (gains), signal-to-noise ratios, and noise-equivalent temperature differences, challenges identified and lessons learned through different phases of on-orbit calibration and characterization are also discussed.

DNB↗
NASA NTRS2021

S-NPP VIIRS Solar Diffuser Degradation at the View Direction of the Rotating Telescope Assembly

S-NPP VIIRS has been on-orbit for more than nine years since it was launched on October28th,2011. The VIIRS reflective solar bands (RSBs) are calibrated on-orbit primarily by an onboard solar diffuser (SD). The SD on-orbit degradation is tracked by an onboard SD stability monitor(SDSM). The VIIRS RSBs view the SD through a rotating telescope assembly (RTA). The RTA views the SD from a direction that is quite different from that of the SDSM. It has been shown that the SD degrades non-uniformly with respect to the incident and outgoing directions, especially at the short wavelengths. Thus, the SDSM calibration cannot provide an accurate SD degradation estimation for the view direction of the RTA, resulting in long-term drifts in the calibration coefficients derived from the SD and SDSM calibration. S-NPP VIIRS has been scheduled to view the Moon approximately monthly since its launch. The lunar observations can provide accurate long-term trends for the RSB calibration coefficients since the lunar surface reflectance is quite stable. By comparing the SD and lunar calibration results, we can obtain the SD degradation differences at the view directions of the SDSM and RTA and derive the SD degradation at the view direction of the RTA. Moreover, we can also derive the SD degradation in the short-wave infrared (SWIR) spectral range, wherein the SDSM cannot track the SD degradation. In this paper, we will derive the SD degradation for the view direction of the RTA from the SD, SDSM, and lunar calibrations from the visible to SWIR spectral range. We will also simulate the SD degradation with analytical models and compare their performances.

SNPP VIIRS↗