Rajendra Bhatt
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View article: A-186 Performance Evaluation of Selected Biochemical Tests Using Sigma Metrics and the Quality Goal Index
A-186 Performance Evaluation of Selected Biochemical Tests Using Sigma Metrics and the Quality Goal Index Open
Background Quality reporting is a critical global concern, necessitating the implementation and evaluation of quality indicators to ensure reliable outcomes. While developed countries have established benchmarks through national policies a…
View article: Regional Characterization of Deep Convective Clouds for Enhanced Imager Stability Monitoring and Methodology Validation
Regional Characterization of Deep Convective Clouds for Enhanced Imager Stability Monitoring and Methodology Validation Open
The NASA CERES project conducts an independent assessment of the calibration stability of MODIS and VIIRS reflective solar bands to ensure consistency in CERES-derived clouds and radiative flux products. The assessment includes the use of …
View article: Advanced Libya-4 radiometric and atmospheric characterization utilizing moderate resolution imaging spectroradiometer and visible infrared imaging radiometer suite full-scan reflective solar band measurements
Advanced Libya-4 radiometric and atmospheric characterization utilizing moderate resolution imaging spectroradiometer and visible infrared imaging radiometer suite full-scan reflective solar band measurements Open
The NASA Clouds and the Earth's Radiant Energy System (CERES) project provides observed flux and cloud products to the climate science community. The CERES instruments, along with the moderate resolution imaging spectroradiometer (MODIS) a…
View article: Early Radiometric Assessment of NOAA-21 Visible Infrared Imaging Radiometer Suite Reflective Solar Bands Using Vicarious Techniques
Early Radiometric Assessment of NOAA-21 Visible Infrared Imaging Radiometer Suite Reflective Solar Bands Using Vicarious Techniques Open
The VIIRS instrument on the JPSS-2 (renamed NOAA-21 upon reaching orbit) spacecraft was launched in November 2022, making it the third sensor in the VIIRS series, following those onboard the SNPP and NOAA-20 spacecrafts, which are operatin…
View article: Utilizing Libya-4 to intercalibrate overlapping sensors in the same sun-synchronous orbit
Utilizing Libya-4 to intercalibrate overlapping sensors in the same sun-synchronous orbit Open
The NASA CERES observed SW and LW broadband fluxes are utilized by the climate community for monitoring the Earth’s energy imbalance and for climate model validation. The SNPP and NOAA20 CERES instruments and associated VIIRS imagers…
View article: The Angular Correction Algorithm for the Intercalibration of Satellite Instruments Using CLARREO Pathfinder as a Reference
The Angular Correction Algorithm for the Intercalibration of Satellite Instruments Using CLARREO Pathfinder as a Reference Open
The Climate Absolute Radiance and Refractivity (CLARREO) Pathfinder (CPF) mission will take Système Internationale (SI)-traceable spectral reflectance measurements of Earth at an unprecedented accuracy of 0.3% (k=1). CPF will also take mea…
View article: Evaluation of systematic errors on polarization parameters from POLDER instrument data for use in CLARREO Pathfinder-VIIRS intercalibration
Evaluation of systematic errors on polarization parameters from POLDER instrument data for use in CLARREO Pathfinder-VIIRS intercalibration Open
One of the Climate Absolute Radiance and Refractivity Observatory Pathfinder (CPF) mission’s science objectives is to intercalibrate the reflective solar bands of the NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aga…
View article: Calibration of the SNPP and NOAA 20 VIIRS sensors for continuity of the MODIS climate data records
Calibration of the SNPP and NOAA 20 VIIRS sensors for continuity of the MODIS climate data records Open
View article: An Assessment of SNPP and NOAA20 VIIRS RSB Calibration Performance in NASA SIPS Reprocessed Collection-2 L1B Data Products
An Assessment of SNPP and NOAA20 VIIRS RSB Calibration Performance in NASA SIPS Reprocessed Collection-2 L1B Data Products Open
Two VIIRS sensors onboard the SNPP and NOAA20 satellites have been successfully operating for over 10 and 4 years, respectively, providing the worldwide user community with high-quality imagery and radiometric measurements of the land, atm…
View article: Radiometric Stability Assessment of the DSCOVR EPIC Visible Bands Using MODIS, VIIRS, and Invariant Targets as Independent References
Radiometric Stability Assessment of the DSCOVR EPIC Visible Bands Using MODIS, VIIRS, and Invariant Targets as Independent References Open
The DSCOVR mission was designed to take advantage of the first Lagrangian position (L1) to continuously observe the Earth sunlit disk. To facilitate EPIC V03 data product validation and fusion, the EPIC V03 navigation and calibration stabi…
View article: Daily monitoring algorithms to detect geostationary imager visible radiance anomalies
Daily monitoring algorithms to detect geostationary imager visible radiance anomalies Open
The NASA Clouds and the Earth's Radiant Energy System (CERES) project provides observed flux and cloud products for the climate science community. Geostationary satellite (GEO) imager measured clouds and broadband derived fluxes are incorp…
View article: Quantifying the Impact of Solar Spectra on the Inter-Calibration of Satellite Instruments
Quantifying the Impact of Solar Spectra on the Inter-Calibration of Satellite Instruments Open
In satellite-based remote sensing applications, the conversion of the sensor recorded top-of-atmosphere reflectance to radiance, or vice-versa, is carried out using a reference spectral solar irradiance (SSI) dataset. The choice of referen…
View article: A kernel-driven BRDF model to inform satellite-derived visible anvil cloud detection
A kernel-driven BRDF model to inform satellite-derived visible anvil cloud detection Open
Satellites routinely observe deep convective clouds across the world. The cirrus outflow from deep convection, commonly referred to as anvil cloud, has a ubiquitous appearance in visible and infrared (IR) wavelength imagery. Anvil clouds a…
View article: Evaluating the Magnitude of VIIRS Out-of-Band Response for Varying Earth Spectra
Evaluating the Magnitude of VIIRS Out-of-Band Response for Varying Earth Spectra Open
Prior evaluations of Visible Infrared Imaging Radiometer Suite (VIIRS) out-of-band (OOB) contribution to total signal revealed specification exceedance for multiple key solar reflective and infrared bands that are of interest to the passiv…
View article: Calibrating Geosynchronous and Polar Orbiting Satellites: Sharing Best Practices
Calibrating Geosynchronous and Polar Orbiting Satellites: Sharing Best Practices Open
Earth remote sensing optical satellite systems are often divided into two categories—geosynchronous and sun-synchronous. Geosynchronous systems essentially rotate with the Earth and continuously observe the same region of the Earth. Sun-sy…
View article: Design and validation of a high-efficiency planar solar thermophotovoltaic system using a spectrally selective emitter
Design and validation of a high-efficiency planar solar thermophotovoltaic system using a spectrally selective emitter Open
This paper presents a detailed-balance analysis required for the achievement of a high-efficiency spectral selective STPV system utilizing thermodynamic and optical modeling approaches. Key parameters affecting the design and optimization …
View article: A kernel-driven BRDF model to inform satellite-derived visible anvil cloud detection
A kernel-driven BRDF model to inform satellite-derived visible anvil cloud detection Open
Satellites routinely observe deep convective clouds across the world. The cirrus outflow from deep convection, commonly referred to as anvil cloud, has a ubiquitous appearance in visible and infrared (IR) wavelength imagery. Anvil clouds a…
View article: Consideration of temperature-dependent emissivity of selective emitters in thermophotovoltaic systems
Consideration of temperature-dependent emissivity of selective emitters in thermophotovoltaic systems Open
Spectral emissivity control is paramount for designing a high-efficiency selective emitter surface required for thermophotovoltaic (TPV) applications. Owing to the temperature dependency of materials optical constants, the spectral propert…
View article: High-efficiency solar thermophotovoltaic system using a nanostructure-based selective emitter
High-efficiency solar thermophotovoltaic system using a nanostructure-based selective emitter Open
View article: Inter-Calibration of the OSIRIS-REx NavCams with Earth-Viewing Imagers
Inter-Calibration of the OSIRIS-REx NavCams with Earth-Viewing Imagers Open
The Earth-viewed images acquired by the space probe OSIRIS-REx during its Earth gravity assist flyby maneuver on 22 September 2017 provided an opportunity to radiometrically calibrate the onboard NavCam imagers. Spatially-, temporally-, an…
View article: The Inter-Calibration of the DSCOVR EPIC Imager with Aqua-MODIS and NPP-VIIRS
The Inter-Calibration of the DSCOVR EPIC Imager with Aqua-MODIS and NPP-VIIRS Open
The Deep Space Climate Observatory (DSCOVR) through the earth polychromatic imaging camera (EPIC) continuously observes the illuminated disk from the Lagrange-1 point. The EPIC sensor was designed to monitor the diurnal variation of ozone,…
View article: An Automated Algorithm to Detect MODIS, VIIRS and GEO Sensor Calibration Discontinuities: GOES-16 Example
An Automated Algorithm to Detect MODIS, VIIRS and GEO Sensor Calibration Discontinuities: GOES-16 Example Open
The CERES project relies on MODIS, VIIRS and geostationary (GEO) imager retrieved cloud properties to compute surface fluxes and convert CERES and GEO radiances into TOA fluxes. The CERES TOA and surface fluxes need to be of climate qualit…
View article: Enhancements to the open access spectral band adjustment factor online calculation tool for visible channels
Enhancements to the open access spectral band adjustment factor online calculation tool for visible channels Open
With close to 40 years of satellite observations, from which, cloud, land-use, and aerosol parameters can be measured, inter-consistent calibrations are needed to normalize retrievals across satellite records. Various visible-sensor inter-…
View article: Consideration of Radiometric Quantization Error in Satellite Sensor Cross-Calibration
Consideration of Radiometric Quantization Error in Satellite Sensor Cross-Calibration Open
The radiometric resolution of a satellite sensor refers to the smallest increment in the spectral radiance that can be detected by the imaging sensor. The fewer bits that are used for signal discretization, the larger the quantization erro…
View article: Characterization of Deep Convective Clouds as an Invariant Target for Satellite SWIR Bands Inter-calibration
Characterization of Deep Convective Clouds as an Invariant Target for Satellite SWIR Bands Inter-calibration Open
Tropical deep convective clouds (DCC) are proven to be an excellent invariant target for post-launch radiometric calibration of satellite visible (VIS) and near-infrared (NIR) spectral channels. The DCC technique (DCCT) is a statistical ap…
View article: Absolute Radiometric Inter-calibration between MODIS and VIIRS Reflective Solar Bands without the use of Simultaneous Observations
Absolute Radiometric Inter-calibration between MODIS and VIIRS Reflective Solar Bands without the use of Simultaneous Observations Open
The CERES project relies on the MODIS and VIIRS sensors for cloud retrievals to convert the CERES observed radiances into fluxes. In order to produce climate quality data records, the cloud properties derived from the MODIS instruments onb…
View article: Geostationary Visible Imager Calibration for the CERES SYN1deg Edition 4 Product
Geostationary Visible Imager Calibration for the CERES SYN1deg Edition 4 Product Open
The Clouds and the Earth’s Radiant Energy System (CERES) project relies on geostationary (GEO) imager derived TOA broadband fluxes and cloud properties to account for the regional diurnal fluctuations between the Terra and Aqua CERES and M…
View article: Development of Seasonal BRDF Models to Extend the Use of Deep Convective Clouds as Invariant Targets for Satellite SWIR-Band Calibration
Development of Seasonal BRDF Models to Extend the Use of Deep Convective Clouds as Invariant Targets for Satellite SWIR-Band Calibration Open
Tropical deep convective clouds (DCC) are an excellent invariant target for vicarious calibration of satellite visible (VIS) and near-infrared (NIR) solar bands. The DCC technique (DCCT) is a statistical approach that collectively analyzes…
View article: Utilizing the precessing orbit of TRMM to produce hourly corrections of geostationary infrared imager data with the VIRS sensor
Utilizing the precessing orbit of TRMM to produce hourly corrections of geostationary infrared imager data with the VIRS sensor Open
Accurate characterization of the Earth's radiant energy is critical for many climate monitoring and weather forecasting applications. For example, groups at the NASA Langley Research Center rely on stable visible- and infrared-channel cali…
View article: Optimization of a Deep Convective Cloud Technique in Evaluating the Long-Term Radiometric Stability of MODIS Reflective Solar Bands
Optimization of a Deep Convective Cloud Technique in Evaluating the Long-Term Radiometric Stability of MODIS Reflective Solar Bands Open
MODIS reflective solar bands are calibrated on-orbit using a solar diffuser and near-monthly lunar observations. To monitor the performance and effectiveness of the on-orbit calibrations, pseudo-invariant targets such as deep convective cl…