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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

The Solar Spectrum: An Atmospheric Remote Sensing Perspective

The solar spectrum not only contains information about the composition and structure of the sun, it also provides a bright and stable continuum source for earth remote sensing (atmosphere and surface). Many types of remote sensors use solar radiation. While high-resolution spaceborne sensors (e.g. ACE) can largely remove the effects of the solar spectrum by exo-atmospheric calibration, this isn't an option for sub-orbital sensors, such as the FTIR spectrometers used in the NDACC and TCCON networks. In this case the solar contribution must be explicitly included in the spectral analysis. In this talk the methods used to derive the solar spectrum are presented, and the underlying solar physics are discussed. Implication for remote sensing are described.

sunlight↗
NASA NTRS1974

Applications of tunable high energy/pressure pulsed lasers to atmospheric transmission and remote sensing

Atmospheric transmission of high energy C12 O2(16) lasers were improved by pulsed high pressure operation which, due to pressure broadening of laser lines, permits tuning the laser 'off' atmospheric C12 O2(16) absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers, and for vertical transmission through the entire atmosphere. The atmospheric transmission of tuned C12 O2(16) lasers compares favorably with C12 O2(18) isotope lasers and CO lasers. The advantages of tunable, high energy, high pressure pulsed lasers over tunable diode lasers and waveguide lasers, in combining high energies with a large tuning range, are evaluated for certain applications to remote sensing of atmospheric constituents and pollutants. Pulsed operation considerably increases the signal to noise ratio without seriously affecting the high spectral resolution of signal detection obtained with laser heterodyning.

Hess, R. V.↗
NASA NTRS2003

Sensitivity analysis of radiative transfer for atmospheric remote sensing in thermal IR: atmospheric weighting functions and surface partials

In this presentation, we apply the adjoint sensitivity analysis of radiative transfer in thermal IR to the general case of the analytic evaluation of the weighting functions of atmospheric parameters together with the partial derivatives for the surface parameters. Applications to remote sensing of atmospheres of Mars and Venus are discussed.

sensitivity analysis remote sensing↗
NASA NTRS2018

Airborne, Direct-Detection, 2-μm Triple-Pulse IPDA Lidar for Simultaneous and Independent Atmospheric Water Vapor and Carbon Dioxide Active Remote Sensing

Atmospheric water vapor and carbon dioxide are important greenhouse gases that significantly contribute to the global radiation budget on Earth. A 2-micron triple-pulse, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric carbon dioxide and water vapor concentration measurements using direct detection was developed at NASA Langley Research Center. This active remote sensing instrument provides an alternate approach with significant advantages for measuring atmospheric concentrations of the gases. A high energy pulsed laser transmitter approach coupled with sensitive receiver detection provides a high-precision measurement capability by having a high signal-to-noise ratio. This paper presents the concept, development, integration and testing of the 2-micron triple-pulse IPDA. The integration includes the various IPDA transmitter, receiver and data acquisition subsystems and components. Ground and airborne testing indicated successful operation of the IPDA lidar.

Refaat, Tamer F.↗
NASA NTRS1987

Excimer laser system for atmospheric remote sensing of ozone

A high-power narrow-linewidth XeCl excimer laser system developed for use by NASA in the remote sensing of atmospheric ozone is described. The laser system is designed for incorporation in a DIAL lidar utilizing stimulated Raman generation for the reference wavelength and sophisticated data averaging techniques. The laser output has a linewidth of 0.002 nm and a beam divergence of 0.15 mrad (FWHM). The laser was operated over a six-hour period with a constant average power of 18 W and a wavelength stable to within + or - 0.0006 nm.

Tan, K. O.↗
NASA NTRSDate not supplied

Neural Network Atmospheric Correction of Remote Sensing Imagery Over Water Using a Synthetic Dataset

Remote sensing atmospheric correction methods have primarily focused on imagery over land. However, accurate correction over water is important for monitoring and research of aquatic environments. More research in this area is ongoing, though one of the biggest challenges is enough quality data to develop and validate correction methods. This is especially true for neural network (NN) -based models which have shown promise in this area given enough quality data. To address this deficiency of data, we are leveraging a synthetic dataset produced by a model called SWIPE that uses radiative transfer modeling to simulate the atmospheric effects on water-leaving (WL) reflectance to estimate top-of-atmosphere (TOA) reflectance. This allows us to produce almost unlimited pairs of WL reflectance and corresponding TOA reflectance for model training across a variety of atmospheric conditions. We use two approaches for our atmospheric correction model. One uses a conditional variational autoencoder (VAE) to estimate a single WL reflectance value from a single TOA reflectance value. The second is based on a UNET architecture and estimates an array of WL reflectance values from an array of TOA reflectance values. The goal of the second method is to capture atmospheric effects that occur spatially between values within the array as compared to the first method.

deep learning↗
NASA NTRS1971

Usefulness of the infrared heterodyne radiometer in remote sensing of atmospheric pollutants.

The application of narrow-band optical receivers to the problem of sensing atmospheric pollution is discussed. The emission/absorption lines of many major atmospheric pollutant molecules overlap the operating frequency bands of CO2 laser and CO laser heterodyne receivers. Several remote pollution sensing systems which are based upon utilization of these spectral overlaps are described, and an analysis of their potential is presented. The possibility of using other lasers (e.g.: the PbSnTe tunable diode laser) as local oscillators is also considered. Results of laboratory experiments with a CO2 laser heterodyne radiometer are presented.

Menzies, R. T.↗
NASA NTRS1983

Passive and active remote sensing of atmospheric precipitation

Both passive and active remote sensing of atmospheric precipitation are studied with the vector radiative transfer equations by making use of the Mie scattering phase functions and incorporating the raindrop-size distributions. For passive remote sensing, the Gaussian quadrature method is employed to solve for the brightness temperatures. For active remote sensing, an iterative approach carrying out to the second order in albedo is used to calculate for the bistatic coefficients, the backscattering cross sections/unit volume, and the interchannel cross talks. The calculated results are plotted as a function of rainfall rates and compared to various available experimental data. The theoretical model is easily applied to the remote sensing of aerosol particles, smoke, fog, and haze at infrared and visible frequencies.

Jin, Y. Q.↗
NASA NTRS1972

Some applications of remote sensing in atmospheric monitoring programs

The applications of remote sensing in atmospheric monitoring programs are described. The organization, operations, and functions of an air quality monitoring network at New Castle County, Delaware is discussed. The data obtained by the air quality monitoring network ground stations and the equipment used to obtain atmospheric data are explained. It is concluded that correlation of the information obtained by the network will make it possible to anticipate air pollution problems in the Chesapeake Bay area before a crisis develops.

Heller, A. N.↗
NASA NTRS1991

Remote sensing of atmospheric chemistry; Proceedings of the Meeting, Orlando, FL, Apr. 1-3, 1991

The present volume on remote sensing of atmospheric chemistry discusses special remote sensing space observations and field experiments to study chemical change in the atmosphere, network monitoring for detection of stratospheric chemical change, stratospheric chemistry studies, and the combining of model, in situ, and remote sensing in atmospheric chemistry. Attention is given to the measurement of tropospheric carbon monoxide using gas filter radiometers, long-path differential absorption measurements of tropospheric molecules, air quality monitoring with the differential optical absorption spectrometer, and a characterization of tropospheric methane through space-based remote sensing. Topics addressed include microwave limb sounder experiments for UARS and EOS, an overview of the spectroscopy of the atmosphere using an FIR emission experiment, the detection of stratospheric ozone trends by ground-based microwave observations, and a FIR Fabry-Perot spectrometer for OH measurements.

Mcelroy, James L.↗
NASA NTRS1972

A review of sphere drag coefficients applicable to atmospheric density sensing

A comprehensive search has been performed on the drag coefficient of spheres in the Reynolds number range from 50 to 50,000 and for Mach numbers up to 5. This Reynolds-Mach number range corresponds to the range of interest in the falling sphere technique of atmospheric sensing. In this technique, the knowledge of the sphere's trajectory and its aerodynamic characteristics are utilized to obtain the density of the atmosphere. Presently available data have been collected and analyzed as to their validity and applicability to atmospheric density measurements. A new drag table is recommended for use in these measurements.

Krumins, M. V.↗
NASA NTRS1984

Applications of airborne remote sensing in atmospheric sciences research

This paper explores the potential for airborne remote sensing for atmospheric sciences research. Passive and active techniques from the microwave to visible bands are discussed. It is concluded that technology has progressed sufficiently in several areas that the time is right to develop and operate new remote sensing instruments for use by the community of atmospheric scientists as general purpose tools. Promising candidates include Doppler radar and lidar, infrared short range radiometry, and microwave radiometry.

Serafin, R. J.↗
NASA NTRS2001

Facility for Atmospheric Remote Sensing (FARS) Cirrus Measurements for FIRE III

From our Facility of Atmospheric Remote Sensing (FARS) in Salt Lake City, Utah, we have since December 1986 collected ground-truth data from cirrus clouds for aiding in satellite cloud detection algorithm testing and improvement, the development of cirrus radiative parameterizations, and basic cloud physics research. This research program has involved data regularly collected with a polarization ruby (0.694 micrometer) lidar system and a suit of passive (visible, infrared, and microwave) radiometers, although a number of comprehensive cloud case studies using the full compliment of remote sensors (i.e., 95 GHz polarimetric Doppler radar and high-resolution dual-wavelength Polarization Diversity Lidar, PDL) have also been obtained. Since our program began, a total of approximately 3,200 hours of lidar/radiometer data have been collected, resulting in a uniquely comprehensive, and climatologically-representative, high cloud dataset. In this report, we highlight our research accomplishments over the period of performance of this grant.

Sassen, Kenneth↗
NASA NTRS1997

Remote Sensing from Geostationary Orbit: GEO TROPSAT, A New Concept for Atmospheric Remote Sensing

The Geostationary Tropospheric Pollution Satellite (GEO TROPSAT) mission is a new approach to measuring the critical constituents of tropospheric ozone chemistry: ozone, carbon monoxide, nitrogen dioxide, and aerosols. The GEO TROPSAT mission comprises a constellation of three instruments flying as secondary payloads on geostationary communications satellites around the world. This proposed approach can significantly reduce the cost of getting a science payload to geostationary orbit and also generates revenue for the satellite owners. The geostationary vantage point enables simultaneous high temporal and spatial resolution measurement of tropospheric trace gases, leading to greatly improved atmospheric ozone chemistry knowledge. The science data processing, conducted as a research (not operational) activity, will provide atmospheric trace gas data many times per day over the same region at better than 25 km ground footprint. The high temporal resolution identifies short time scale processes, diurnal variations, seasonal trends, and interannual variation.

Little, Alan D.↗