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Frederick Patt

Publications and source records attributed to Frederick Patt.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

PACE OCI Lunar Calibration: Initial Results

Launched in February 2024, the Ocean Color Instrument (OCI) onboard NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission has started performing its monthly lunar calibrations at ±7degreeslunar phase angle in March 2024. In this paper, we will describe the OCI lunar calibration methodology and show the results of lunar calibration events during the initial months of PACE/OCI operation. A key difference of OCI lunar calibration from heritage sensors is that the lunar disk integrated irradiance is computed from lunar pixel radiance and sampling distance instead of the instrument’s IFOV. PACE provided a near constant sweep rate during lunar calibration allowing accurate determination of OCI pixel sampling extent. OCI performs lunar calibration in baseline science mode with 282 hyperspectral bands from 315 –895 nm and 7 shortwave infrared bands(940 -2260 nm). For each OCI band, we compute the integrated lunar disk irradiance, and compare the result with a lunar irradiance model (ROLO)prediction. The early results presented here clearly show that OCI’s lunar image acquisition is working as intended and will provide accurate data for OCI’s on-orbit radiometric characterization. The hyperspectral lunar irradiances provided by OCI are expected to become a valuable data set for the evaluation of lunar irradiance models.

calibration↗
NASA NTRSDate not supplied

Life After Launch: A Snapshot of the First 6 Months of NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) Mission

The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission launched from Kennedy Space Center in the early morning of February 8, 2024. Just 63 days later, data from NASA’s newest Earth-observing satellite became available to the public. These data will extend and improve upon NASA’s 20+ years of global satellite observation of our living oceans, atmospheric aerosols, and cloud and initiate an advanced set of climate-relevant data records. Ultimately, PACE is the first mission to provide daily, global measurements that will enable prediction of the “boom-bust” cycle of fisheries, the appearance of harmful algae, and other factors that affect commercial and recreational industries. PACE also observes clouds and tiny airborne particles known as aerosols that influence air quality and absorb and reflect sunlight, thus warming and cooling the atmosphere. In the months since launch and initial data release, the PACE Project pursued instrument temporal and system vicarious calibrations, executed cross-instrument comparisons, conducted performance assessments, explored synergies with other missions, and released advanced science data products. In parallel, the PACE Validation Science Team left for the field and the Post-launch Airborne eXperiment (PACE-PAX) prepared for its mission. And, most importantly, preliminary science results were realized. Here, we present a snapshot of these activities and their impacts and outcomes, encompassing the first half year of the PACE mission.

PACE↗
NASA NTRSDate not supplied

PACE OCI Straylight and Crosstalk Evaluation using Moon

The Ocean Color Instrument (OCI) onboard NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission has performed three monthly lunar calibrations. The moon is an extended source over a large dark background, making it an ideal target for evaluating OCI’s straylight and crosstalk performance. The lunar data analysis showed the straylight and crosstalk to be lower than the prelaunch measurements, especially in the along-track direction, where very little straylight is detected. Based on lunar data, the prelaunch measured crosstalk coefficients were reduced, and a crosstalk correction was tested on both lunar and solar calibration data. Applying the revised crosstalk correction, the crosstalk contaminations are significantly reduced to under 0.1% at 2-3 pixels away from the lunar boundary for bands above 350 nm. Below 350 nm, the crosstalk correction residuals gradually increase due to a lack of high-quality prelaunch measurements. Lastly, applying the crosstalk correction changes the calibrated radiance for all science data. This is due to the different spectral shapes between the solar diffuser and the observed scenes. For the moon, the crosstalk correction has an impact of ~0.4% on the overall calibrated radiance for the 400 – 600 nm bands and up to 20% impact on the UV bands.

Shihyan Lee↗