This study presents a first-of-its-kind comprehensive data fusion approach combining hyperspectral microwave (HMW) with backscatter lidar (BSL) measurements for improved atmospheric thermodynamic sounding, with particular emphasis on the Earth’s Planetary Boundary Layer (PBL). This is a simulation-based trade study to demonstrate the enhancement of HMW over traditional microwave (MW) only measurements and the additional benefits of incorporating BSL with both approaches. This pioneering HMW+BSL fusion methodology represents a major advancement, achieving superior performance compared to traditional thermodynamic remote sensing approaches. Specifically, this configuration demonstrates significant enhancement in PBL temperature bias vertical stability and reduces standard deviation error (SDV) by 30% compared to traditional MW-only performance. Water vapor retrievals show similar improvements, with SDV reductions of 50% in the PBL and bias values consistently maintained below the 10% requirement threshold of the PBL DSI program, compared to PoR errors exceeding 30% bias in challenging cloudy regimes. Case studies across diverse oceanic regions reveal particular advantages of this data fusion approach in complex atmospheric conditions, especially in regions dominated by marine stratocumulus clouds and strong temperature inversions where conventional passive-only retrievals are challenging. Beyond thermodynamic profile improvements, our analysis demonstrates remarkable advances in the detection of PBL height (PBLH), with the HMW+BSL configuration achieving mean absolute errors within the 100 meter requirement threshold of the PBL DSI program, representing a step-change improvement over passive-only approaches. This work directly addresses observational gaps identified in the 2017 Earth Science Decadal Survey, positioning our integrated sensing approach as both a near-term enhancement to existing Earth observation capabilities and a pathfinder for future PBL mission architectures.

The Orbiting Carbon Observatory-3 (OCO-3) instrument, operated from the International Space Station, was launched on May 4, 2019. Its primary objective is to provide high-precision estimates of the column-averaged dry-air mole fraction of carbon dioxide (XCO2) and solar-induced chlorophyll fluorescence. It consists of three long-slit imaging spectrometers that provide high-resolution spectra in three infrared bands. The shortest wavelength one, named A-band, is centered at$0.765~\mu $m and characterized by numerous absorption lines of molecular oxygen. Throughout the mission, this band has undergone important changes in instrument response related to contamination of the focal plane array (FPA). One way contamination buildup affects OCO-3 A-band data is by imparting an S-like shape to the observed spectra, which cannot be characterized and corrected through analysis of data from the onboard calibrator alone. In Version 10, this artifact manifested itself as a slow drift of XCO2, from February 2020 to January 2021, and required an additional postretrieval bias correction. In the latest collection, Version 11, OCO-3’s inflight calibration algorithm for the A-band was augmented to correct this artifact using clear ocean scenes to derive the spectral shape of changes in instrument response. This drastically improved the shape of spectral residuals between observed and forward modeled radiances and also significantly reduced the slow XCO2 drift observed in Version 10.

We present an overview of the 2024 West-Coast Hyperspectral Microwave Sensor Intensive Experiment (WHyMSIE). WHyMSIE is a joint NASA-NOAA multi-sensor airborne experiment, embracing passive and active sensors from the Program of Record (PoR) along with novel technology funded through the NASA ESTO Instrument Incubation Program. At the core of this effort is the demonstration of the Conical Scanning Millimeter-wave Imaging Radiometer Hyperspectral (CoSMIR-H) instrument, a PBL DSI funded effort to develop hyperspectral sounding capability in the thermal microwave domain finalized to improved temperature and water vapor soundings in the Earth’s Planetary Boundary Layer (PBL). An overview of the field campaign design, instrument payload and validation plan is presented here.

We present a comprehensive Earth Planetary Boundary Layer temperature and water vapor retrieval improvement demonstration by the use of hyperspectral microwave measurements. Our results indicate that the use of a hyperspectral sampling in the oxygen and water vapor sounding lines alone provides significant improvements in the lower and free tropospheric thermodynamic fields (up to 40%), when compared against the program of record (i.e., the Advanced Technology Microwave Sounder, ATMS). Our experiments also demonstrate the essential role played by extending the coverage in the so called spectral window regions, leading to an overall PBL temperature and water vapor improvement of up to 50%.

The Orbiting Carbon Observatory (OCO) -2 and -3 instruments, launched in 2014 and 2019 respectively, require accurate and precise calibration to achieve science goals. While onboard lamps and solar diffusers have proven very useful to track changes over short time scales, these calibration sources have themselves exhibited substantial degradation over the extended mission life. OCO-2 has relied on lunar measurements to estimate "slow" irreversible changes in radiometric response, and OCO-3 is attempting to do the same. This work describes how each instrument observes the Moon and highlights key differences in how these datasets are acquired. Several near-coincident observations also present the opportunity to join the two records, which will benefit both missions.

This paper presents an overview of the Hyperspectral Microwave Photonic Instrument (HyMPI), a 2021 NASA Instrument Incubation Proposal funded project aimed at developing the very first hyperspectral microwave sensor to augment thermodynamic sounding capability from space, with a focus on the Earth's Planetary Boundary Layer. This research responds to the recommendation expressed in the 2018 National Academies of Sciences decadal survey to accelerate the readiness of high-priority PBL observables not feasible for cost-effective spaceflight in 2017–2027. This paper provides an overview on HyMPI's design, configured as the objective instrument concept needed to fly in the future PBL mission and presents preliminary trade studies aim at demonstrating HyMPI's enhanced thermodynamic sounding skill in the Earth's Planetary Boundary Layer over conventional microwave sounders from the current Program of Record.

The Orbiting Carbon Observatory-3 (OCO-3) measures carbon dioxide and solar-induced fluorescence from the International Space Station (ISS). It uses the flight spare spectrometers from its predecessor, OCO-2, and produces spectral images in three near-infrared channels. Its preflight radiometric calibration was performed at NASA’s Jet Propulsion Laboratory and is constantly updated inflight to account for both gradual and abrupt changes in instrument response that display a wavelength dependency within the bands. Some of these are caused by the accumulation of contaminants and their subsequent removal after scheduled decontamination events, but sudden changes of the overall gain state of the two longest wavelength bands, unrelated to contamination, are also observed. They were found to be triggered by instrument resets as well as by decontamination events. OCO-3 cannot perform solar calibration due to its position on the ISS and the inflight updates to its radiometric calibration depend solely on its on-board calibrator, which consists of three lamps and a reflective diffuser. The lamps are observed with different cadences and thus degrade at different rates. Information from all three lamps is combined to provide high temporal resolution and minimize the impact of lamp aging on the gain degradation coefficients that describe the changes in the radiometric response of the instrument inflight. We use thousands of soundings from ocean scenes to assess the relative calibration within the two shortest wavelength bands. Here we present the algorithm developed for the inflight relative radiometric calibration of OCO-3 Version 10 products and discuss the state of the calibration.

The third major reprocessing campaign for the Orbiting Carbon Observatory 2 mission is underway. With each release, several aspects of instrument calibration were improved. An onboard lamp tracks relative gain degradation, but ages too quickly to track absolute scaling. The most significant changes between builds were evolving assumptions about the stability of the solar calibrator. For the newest build, the trend in lunar measurements over a 4.5-year time series was applied. Another significant change was to expand a list of detector outliers via review of dark, lamp, and science measurements. More subtle adjustments to stray light and spectral dispersion were also performed. The techniques developed for OCO-2 are being applied to the Orbiting Carbon Observatory 3, which completed in-orbit checkout in August 2019. OCO-3 does not have a solar calibrator, and will need to constrain lamp aging via secondary lamps and comparison to other satellites.

The Orbiting Carbon Observatory - 3 (OCO-3) is a NASA Earth-monitoring instrument, designed and built by the Jet Propulsion Laboratory (JPL) to perform space-based observation of variations of global carbon dioxide (CO2) by sampling its emission sources and gradients from the unique vantage point of the International Space Station (ISS). This paper describes the development and results of the end-to-end verification, validation, and calibration activities that were performed to meet OCO-3's science, functional, and performance requirements prior to launch. The pre-launch activities encompassed a suite of tests and analyses that were performed after instrument assembly and prior to launch vehicle integration to demonstrate launch and mission readiness in terms of ISS compatibility, ground-based instrument calibrations, flight dynamics, environmental integrity, and pointing knowledge and accuracy.

Vicarious calibration methods use well-characterized surface sites to complement other on-orbit radiometric calibration techniques. Since 2009, NASA's Orbiting Carbon Observatory-2 (OCO-2) and Japan's Greenhouse gasses Observing SATellite teams have conducted annual campaigns at Railroad Valley, NV, USA, for this purpose. These sensors pose special challenges due to their large footprint sizes and view angles. OCO-2 sweeps the playa surface during a targeted overpass of the test site, and records data at a number of viewing angles. The smallest of these is selected for processing, thereby minimizing the off-nadir correction. Surface reflectances at nadir are recorded by the field team, and the Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance product is used to provide the small, off-nadir correction. Another MODIS product, the Level 1B top-of-atmosphere radiance product, is used to validate the results and to provide input into the OCO-2 calibration uncertainty estimate. From 11 experiments, the ratio of radiances reported by the OCO-2 Level 1B data product to those from the field campaigns is 1.01, 1.04, and 1.01 for the three OCO-2 spectral bands. These analyses validate the data product absolute calibration, to within the 5% requirement. The need for executing these experiments will be of continued importance to OCO-3. This sensor has an on-board calibrator that provides a dark signal and lamps for response trends but does not have the on-board solar-diffuser present on OCO-2, and thus cannot track degradations relative to the Sun.

This paper describes the preflight spectral calibration methods and results for the Orbiting Carbon Observatory 2 (OCO-2), following the approach developed for the first OCO. The instrument line shape (ILS) function and dispersion parameters were determined through laser-based spectroscopic measurements, and then further optimized by comparing solar spectra recorded simultaneously on the ground by the OCO-2 flight instrument and a collocated high-resolution Fourier transform spectrometer (FTS). The resulting ILS profiles and dispersion parameters, when applied to the FTS solar data, showed agreement between the spectra recorded by the spectrometers and FTS to approximately 0.2% RMS, satisfying the preflight spectral calibration accuracy requirement of <;0.25% RMS. Specific changes to the OCO-2 instrument and calibration process, compared to the original OCO, include stray-light protection; improved laser setup; increased spectral sampling; enhanced data screening, and incremental improvements in the ILS, dispersion, and FTS optimization analyses.

The imaging spectrometers of the second orbiting carbon observatory were radiometrically calibrated before launch during instrumentlevel ground testing. The gain and dark responses were characterized for each focal plane array detector element. An integrating sphere source with an integrated monitoring spectroradiometer illuminated the OCO-2 spectrometers at many light levels. Instrument output was compared with the calibrated output of the source to derive gain coefficients. This source was calibrated in situ with respect to the National Institute of Standards and Technology reference standards, and the instrument met its absolute performance requirement of 5%. Matching fields of view for the internal monitor detectors and the external instrument under test was found to be particularly important, as observed in the results and supported by modeling. Temperature-dependent dark offsets were corrected in a separate process. Solar spectra with varying neutral density filters were used to validate the linearity of the spectrometers.

Computational complexity theory inspires a grid-free abstraction of the Navier-Stokes equations in Fortran 95/2003. A novel complexity analysis estimates that structured programming time grows at least quadratically with the number of program lines. Further analysis demonstrates how an object-oriented strategy focused on mathematical objects renders the quadratic estimate scale-invariant, so the time required for the limiting factor in program development (debugging) no longer grows as the code grows. Compared to the coordinate-free C++ programming of Grant et al. [2000], grid-free Fortran programming eliminates a layer of procedure calls, eliminates a related need for the C++ template construct, and offers a shorter migration path for Fortran programmers. The grid-free strategy is demonstrated by constructing a physical-space driver for a Fourier-space Navier-Stokes solver. Separating the expression of the continuous mathematical model from the discrete numerics clarifies issues that are otherwise easily conflated. A run-time profile suggests that grid-free design substantially reduces the fraction of the procedures that significantly impact runtime, freeing more code to be structured in ways that reduce development time. Applying Amdahl's law to the total solution time (development time plus run time) leads to a strategy that negligibly impacts development time but achieves 58% of the maximum possible speedup.

Accurate modeling of pulse propagation and scattering is of great importance to the Navy. In a non-dispersive medium a fourth order in time and space 2-D Finite Difference Time Domain (FDTD) scheme representation of the linear wave equation can be used. However when the medium is dispersive one is required to take into account the frequency dependent attenuation and phase velocity. Using a theory first proposed by Blackstock, the linear wave equation has been modified by adding an additional term (the derivative of the convolution between the causal time domain propagation factor and the acoustic pressure) that takes into account the dispersive nature of the medium. This additional term transforms the calculation from one suitable to a workstation into one very much suited to a largescale computational platform, both in terms of computation and memory. With appropriate distribution of data, good scaling can be achieved up to thousands of processors. Due to the simple structure of the code, it is easily parallelized using three different techniques: pure MPI, pure OpenMP and a hybrid MPI/OpenMP. We use this real life application to evaluate the performance of the latest multi-cpu/multicore platforms available from the DoD HPCMP.

We describe our experiences porting and tuning three scientific programs to the Cray MTA-2, paying particular attention to the problems posed by I/O. We have measured the performance of each of the programs over many different machine configurations and we report on the scalability of each program. In addition, we compare the performance of the MTA with that of an SGI Origin running all three programs.

We describe the efforts being carried out at the Naval Research Laboratory (NRL) towards VR scientific visualization. We are exploring scientific visualization in an immersive virtual environment: the NRL's CAVE/sup TM/-like device known as GROTTO (Graphical room for observation, Training and Tactical Orientation). We describe the AVS GROTTO viewer, a VR interface to the AVS visualization system. The AVS GROTTO viewer has been used by a number of scientists in current, ongoing research projects within NRL.

This case study describes a technique for the three-dimensional analysis of the internal microscopic structure (microstructure) of materials. This technique consists of incrementally polishing through a thin layer (approximately 0.2 /spl mu/m) of material, chemically etching the polished surface, applying reference marks, and performing optical or scanning electron microscopy on selected areas. The series of images are then processed employing AVS and other visualization software to obtain a 3D reconstruction of the material. We describe how we applied this technique to an alloy steel to study the morphology, connectivity, and distribution of cementite precipitates formed during thermal processing. The results showed microstructural features not previously identified with traditional 2D techniques.

The Virtual Workbench (VW) is a non-immersive virtual environment that allows users to view and interact with stereoscopic objects displayed on a workspace similar to a tabletop workspace used in day-to-day life. A VW is an ideal environment for collaborative work where several colleagues can gather around the table to study 3D virtual objects. The Virtual Reality laboratory at the Naval Research Laboratory has implemented the VW using a concept similar to (Froehlich et al., 1994). This paper investigates how the VW can be used as a non-immersive display device for understanding and interpreting complex objects encountered in the scientific visualization field. Different techniques for interacting with 3D visualization objects on the table and using VW as a display device for visualization are evaluated using several cases.