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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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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Evaluation of 2-μm Pulsed Integrated Path Differential Absorption Lidar for Carbon Dioxide Measurement—Technology Developments, Measurements, and Path to Space

The societal benefits of understanding climate change through the identification of global carbon dioxide sources and sinks led to the recommendation for NASA's Active Sensing of Carbon Dioxide Emissions over Nights, Days, and Seasons space-based mission for global carbon dioxide measurements. For more than 15 years, the NASA Langley Research Center has developed several carbon dioxide active remote sensors using the differential absorption lidar technique operating at 2-μm wavelength. Recently, an airborne double-pulsed integrated path differential absorption lidar was developed, tested, and validated for atmospheric carbon dioxide measurement. Results indicated 1.02% column carbon dioxide measurement uncertainty and 0.28% bias over the ocean. Currently, this technology is progressing toward triple-pulse operation targeting both atmospheric carbon dioxide and water vapor-the dominant interfering molecule on carbon dioxide remote sensing. Measurements from the double-pulse lidar and the advancement of the triple-pulse lidar development are presented. In addition, measurement simulations with a space-based IPDA lidar, incorporating new technologies, are also presented to assess feasibility of carbon dioxide measurements from space.

Singh, Upendra N.↗
NASA NTRS2015

Double-Pulse Two-Micron IPDA Lidar Simulation for Airborne Carbon Dioxide Measurements

An advanced double-pulsed 2-micron integrated path differential absorption lidar has been developed at NASA Langley Research Center for measuring atmospheric carbon dioxide. The instrument utilizes a state-of-the-art 2-micron laser transmitter with tunable on-line wavelength and advanced receiver. Instrument modeling and airborne simulations are presented in this paper. Focusing on random errors, results demonstrate instrument capabilities of performing precise carbon dioxide differential optical depth measurement with less than 3% random error for single-shot operation from up to 11 km altitude. This study is useful for defining CO2 measurement weighting, instrument setting, validation and sensitivity trade-offs.

Refaat, Tamer F.↗
NASA NTRS2017

Triple-Pulse Integrated Path Differential Absorption Lidar for Carbon Dioxide Measurement - Novel Lidar Technologies and Techniques with Path to Space

The societal benefits of understanding climate change through identification of global carbon dioxide sources and sinks led to the desired NASA's active sensing of carbon dioxide emissions over nights, days, and seasons (ASCENDS) space-based missions of global carbon dioxide measurements. For more than 15 years, NASA Langley Research Center (LaRC) have developed several carbon dioxide active remote sensors using the differential absorption lidar (DIAL) technique operating at the two-micron wavelength. Currently, an airborne two-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development. This IPDA lidar measures carbon dioxide as well as water vapor, the dominant interfering molecule on carbon dioxide remote sensing. Advancement of this triple-pulse IPDA lidar development is presented.

Singh, Upendra N.↗
NASA NTRS2011

Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

Singh, Upendra N.↗
NASA NTRS2008

Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

Singh, Upendra N.↗
NASA NTRS2019

Frequency Control of Multi-Pulse 2-micron Laser Transmitter for Atmospheric Carbon Dioxide Measurement

Laser sources with highly stabilized emission wavelength is of paramount importance for a long term atmospheric carbon dioxide (CO2) measurement from a space platform. Integrated Path Differential Absorption (IPDA) lidar is a promising instrument for such a task. The design of a laser transmitter, with emphasis on the method used to control and select several wavelengths, is presented. This multi-pulsed, injection seeded, 2-μm transmitter uses a Ho:Tm:YLF laser crystal which has matching emission to the absorption of CO2 in the R30 spectroscopic area. The injection seeded laser produces triple single longitudinal mode transform limited line width pulses with a total of 80 mJ at a repetition rate of 50 Hz.

Petros, Mulugeta↗
NASA NTRS1980

Carbon dioxide measurements in the stratosphere

A mass spectrometer experiment for the analysis of minor constituents in the stratosphere has been flown successfully four times from Palestine, Texas on board a balloon gondola. The carbon dioxide mixing ratio, which shows unexpectedly large variations in the stratosphere, reached 400 ppm in one particular night flight. This is about 20% higher than the ground value. Evidence is presented that the experiment performed well during each of the balloon flights. The isotopic ratio C-12/C-13 was measured and found in good agreement with previous air analyses showing a depletion of C-13.

Mauersberger, K.↗
NASA NTRS2014

Field Results from Three Campaigns to Validate the Performance of the Miniaturized Laser Heterodyne Radiometer (Mini‐LHR) for Measuring Carbon Dioxide and Methane in the Atmospheric Column

In a collaboration between NASA GSFC and GWU, a low-cost, surface instrument is being developed that can continuously monitor key carbon cycle gases in the atmospheric column: carbon dioxide (CO2) and methane (CH4). The instrument is based on a miniaturized, laser heterodyne radiometer (LHR) using near infrared (NIR) telecom lasers. Despite relatively weak absorption line strengths in this spectral region, spectrallyresolved atmospheric column absorptions for these two molecules fall in the range of 60-80% and thus sensitive and precise measurements of column concentrations are possible. In the last year, the instrument was deployed for field measurements at Park Falls, Wisconsin; Castle Airport near Atwater, California; and at the NOAA Mauna Loa Observatory in Hawaii. For each subsequent campaign, improvement in the figures of merit for the instrument has been observed. In the latest work the absorbance noise is approaching 0.002 optical density (OD) noise on a 1.8 OD signal. An overview of the measurement campaigns and the data retrieval algorithm for the calculation of column concentrations will be presented. For light transmission through the atmosphere, it is necessary to account for variation of pressure, temperature, composition, and refractive index through the atmosphere that are all functions of latitude, longitude, time of day, altitude, etc. For temperature, pressure, and humidity profiles with altitude we use the Modern-Era Retrospective Analysis for Research and Applications (MERRA) data. Spectral simulation is accomplished by integrating short-path segments along the trajectory using the SpecSyn spectral simulation suite developed at GW. Column concentrations are extracted by minimizing residuals between observed and modeled spectrum using the Nelder-Mead simplex algorithm. We will also present an assessment of uncertainty in the reported concentrations from assumptions made in the meteorological data, LHR instrument and tracker noise, and radio frequency bandwidth and describe additional future goals in instrument development and deployment target

meteorological data↗
NASA NTRS2002

Progress on Passive Sensor for Ultra-Precise Measurement of Carbon Dioxide from Space

Global measurements of atmospheric carbon dioxides (CO2) are needed to resolve significant discrepancies that exist in our understanding of the global carbon budget and, therefore, man's role in global climate change. The science measurement requirements for CO2 are extremely demanding (precision c .3%) No atmospheric chemical species has ever been measured from space with this precision. We are developing a novel application of a Fabry-Perot interferometer to detect spectral absorption of reflected sunlight by CO2 and O2 in the atmosphere. Preliminary design studies indicate that the method will be able to achieve the sensitivity and signal-to-noise required to measure column CO2 at the target specification. We are presently engaged in the construction of a prototype instrument for deployment on an aircraft to test the instrument performance and our ability to retrieve the data in the real atmosphere. In the first 6 months we have assembled a laboratory bench system to begin testing the optical and electronic components. We are also undertaking some measurements of signal and noise levels for actual sunlight reflecting from the ground. We shall present results from some of these ground based studies and discuss their implications for a space based system.

Heaps, William S.↗
NASA NTRS2007

Precise Measurement of Carbon Dioxide Column by Passive Ground Based Sensor

Over the past four years we have developed a family of differential radiometers based upon the Fabry-Perot interferometers that exhibit very great sensitivity to changes in the atmospheric column of carbon dioxide, oxygen, and water vapor. Our instruments employ a solid Fabry-Perot etalon that is tuned to the proper wavelength by changing its temperature. The thickness of the etalon has been selected so that its multiple pass bands align with regularly space absorption features of the molecule under investigation. Using multiple absorption features improves the optical throughput of the instrument and improves the stability of the instrument response with respect to environmental changes. We are presently working to extend this technique to the carbon 13 isotope of carbon dioxide and to methane. Our instruments are intrinsically rugged and can be fabricated in a small package at relatively low cost.. As such they hold promise for widespread use in ground based networks for calibration and validation of satellite instruments such as OCO and GOSAT. Results will be presented for long term ground based operations of these systems. The effects of atmospheric scattering, pointing errors, pressure broadening and temperature effects will be discussed with regard to achieving precision better than .5% required for validation of carbon dioxide column measured from space. Finally we will outline the approach for extension of this methodology to additional molecular species of interest.

Heaps, William S.↗
NASA NTRS1991

Analysis of field measurements of carbon dioxide and water vapor fluxes

Analysis of the field measurements of carbon dioxide and water vapor fluxes is discussed. These data were examined in conjunction with reflectance obtained from helicopter mounted Modular Multiband Radiometer. These measurements are representative of the canopy scale (10 to 100 m)(exp 2) and provide a good basis for investigating the hypotheses/relationship potentially useful in remote sensing applications. All the micrometeorological data collected during FIFE-89 were processed and fluxes of CO2, water vapor, and sensible heat were calculated. Soil CO2 fluxes were also estimated. Employing these soil CO2 flux values, in conjunction with micrometeorological measurements, canopy photosynthesis is being estimated. A biochemical model of leaf photosynthesis was adapted to the prairie vegetation. The modeled leaf photosynthesis rates were scaled up to the canopy level. This model and a multiplicative stomatal conductance model are also used to calculate canopy conductance.

Verma, Shashi B.↗