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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Remote Sensing of Earth's Surface and Atmosphere: Interdisciplinary Scientific Commission A of the COSPAR Plenary Meeting, 29th, Washington, DC, 28 Aug. - 5 Sep., 1992

This conference reviewed the recent developments in remote monitoring of surface temperatures, which will be significant in future global change studies. Various techniques to derive surface temperature from existing and future remote sensing systems such as earth observing system (EOS) are discussed. Five sessions were held: (1) The nature of the problem of remote sensing of surface temperatures; (2) Surface temperature measurements from current satellites; (3) Modeling and surface observations of various techniques to measure temperature and/or emissivity, modeling of vegetation; (4) The effects of variable spectral emissivity from the determination of surface kinetic temperature using multispectral thermal infrared measurements; and (5) Future satellite systems including EOS/ASTER, EOS/MODIS-N, and EOS/AIRS.

Kahle, A. B.↗
NASA NTRS1986

Atmospheric-water absorption features near 2.2 micrometers and their importance in high spectral resolution remote sensing

Selective absorption of electromagnetic radiation by atmospheric gases and water vapor is an accepted fact in terrestrial remote sensing. Until recently, only a general knowledge of atmospheric effects was required for analysis of remote sensing data; however, with the advent of high spectral resolution imaging devices, detailed knowledge of atmospheric absorption bands has become increasingly important for accurate analysis. Detailed study of high spectral resolution aircraft data at the U.S. Geological Survey has disclosed narrow absorption features centered at approximately 2.17 and 2.20 micrometers not caused by surface mineralogy. Published atmospheric transmission spectra and atmospheric spectra derived using the LOWTRAN-5 computer model indicate that these absorption features are probably water vapor. Spectral modeling indicates that the effects of atmospheric absorption in this region are most pronounced in spectrally flat materials with only weak absorption bands. Without correction and detailed knowledge of the atmospheric effects, accurate mapping of surface mineralogy (particularly at low mineral concentrations) is not possible.

Kruse, F. A.↗
NASA NTRS2003

Atmospheric Boundary Layer Sensors for Application in a Wake Vortex Advisory System

Remote sensing of the atmospheric boundary layer has advanced in recent years with the development of commercial off-the-shelf (COTS) radar, sodar, and lidar wind profiling technology. Radio acoustic sounding systems for vertical temperature profiles of high temporal scales (when compared to routine balloon soundings- (radiosondes) have also become increasingly available as COTS capabilities. Aircraft observations during landing and departures are another source of available boundary layer data. This report provides an updated assessment of available sensors, their performance specifications and rough order of magnitude costs for a potential future aircraft Wake Vortex Avoidance System (WakeVAS). Future capabilities are also discussed. Vertical profiles of wind, temperature, and turbulence are anticipated to be needed at airports in any dynamic wake avoidance system. Temporal and spatial resolution are dependent on the selection of approach and departure corridors to be protected. Recommendations are made for potential configurations of near-term sensor technologies and for testing some of the sensor systems in order to validate performance in field environments with adequate groundtruth.

Zak, J. Allen↗
NASA NTRS1987

Remote sensing of the earth's biosphere - A tool for studies of the global atmospheric environment

Recent advances in remote sensing technology and its use for global studies of the biospheric processes are described. Special consideration is given to research related to two issues: (1) quantifying the impacts of natural vegetation and its changing patterns of occurrence on the atmospheric CO2 budget and (2) assessing wetlands (such as the swamps and marshes of Florida's Everglades) as sources of atmospheric CH4. The results include the data from NOAA-AVHRR sensors and from experiments in remote detection of plant growth rate.

Bartlett, David S.↗
NASA NTRS2015

Remote Sensing of Aerosol in the Terrestrial Atmosphere from Space: New Missions

The distribution and properties of atmospheric aerosols on a global scale are not well known in terms of determination of their effects on climate. This mostly is due to extreme variability of aerosol concentrations, properties, sources, and types. Aerosol climate impact is comparable to the effect of greenhouse gases, but its influence is more difficult to measure, especially with respect to aerosol microphysical properties and the evaluation of anthropogenic aerosol effect. There are many satellite missions studying aerosol distribution in the terrestrial atmosphere, such as MISR/Terra, OMI/Aura, AVHHR, MODIS/Terra and Aqua, CALIOP/CALIPSO. To improve the quality of data and climate models, and to reduce aerosol climate forcing uncertainties, several new missions are planned. The gap in orbital instruments for studying aerosol microphysics has arisen after the Glory mission failed during launch in 2011. In this review paper, we describe several planned aerosol space missions, including the Ukrainian project Aerosol-UA that obtains data using a multi-channel scanning polarimeter and wide-angle polarimetric camera. The project is designed for remote sensing of the aerosol microphysics and cloud properties on a global scale.

Aerosol↗
NASA NTRS1976

Remote sensing of chlorophyll in an atmosphere-ocean environment - A theoretical study

A Monte Carlo program was written to compute the effect of chlorophyll on the ratio of upwelling to downwelling radiance and irradiance as a function of wavelength, height above the ocean, and depth within the ocean. This program simulates the actual physical situation, since a real atmospheric model was used, i.e., one that contained both aerosol and Rayleigh scattering as well as ozone absorption. The complete interaction of the radiation field with the ocean was also taken into account. The chlorophyll was assumed to be uniformly mixed in the ocean and was also assumed to act only as an absorbing agent. For the ocean model both scattering and absorption by hydrosols was included. Results have been obtained for both a very clear ocean and a medium turbid ocean. Recommendations are made for optimum techniques for remotely sensing chlorophyll both in situ and in vitro.

Kattawar, G. W.↗
NASA NTRS1997

Remote Sensing of Multi-Level Wind Fields with High-Energy Airborne Scanning Coherent Doppler Lidar

The atmospheric lidar remote sensing groups of NOAA Environmental Technology Laboratory, NASA Marshall Space Flight Center, and Jet Propulsion Laboratory have developed and flown a scanning, 1 Joule per pulse, CO2 coherent Doppler lidar capable of mapping a three-dimensional volume of atmospheric winds and aerosol backscatter in the troposphere and lower stratosphere. Applications include the study of severe and non-severe atmospheric flows, intercomparisons with other sensors, and the simulation of prospective satellite Doppler lidar wind profilers. Examples of wind measurements are given for the marine boundary layer and near the coastline of the western United States.

Rothermel, Jeffry↗
NASA NTRS1982

Advanced sensors for spaceborne measurements of the earth's atmosphere

Concepts involved in remote sensing from space are reviewed, together with performance requirements of proposed and planned equipment. Attention is focused on measurements of the troposphere, particularly meteorological variables and chemical species. The principles of absorption, using either passive or active sensors, emission detection, fluorescence measurements, and EM radiation scattering are outlined. The proposed NASA Windsat, using a CO2 laser from the Orbiter or from an 800 km orbit spacecraft to measure low-level wind speeds is described, as are the uses of the AMTS atmospheric sounder instrument for IR atmospheric temperature sensing and a 20-channel microwave radiometer to detect moisture profiles in the water vapor bands. Additionally, a microwave pressure sounder to detect backscattered signals at 60 GHz is outlined, along with lidar pressure and wind speed measurement methods.

Hinkley, E. D.↗
NASA NTRS1982

Remote sensing of temperature profiles in the atmosphere

Methods of regularized and generalized cross validation can be used to estimate the atmosphere's temperature, moisture, and wind structure from a finite number m noisy measurements by meteorological satellites on the intensity of upwelling radiation in selected channel frequencies. The inversion of the equation of radiative transfer is discussed for data obtained by TIROS N satellite.

Osullivan, F.↗
NASA NTRS1994

Remote sensing of turbulence in the clear atmosphere with 2-micron lidars

The development of an eye-safe, airborne LIDAR that exploits the decorrelation of the heterodyne signal to detect clear air turbulence is reported. A one watt average power transmitter is capable of detecting clear air turbulence to over 20 km is subvisual cirrus (an environment highly correlated with instabilities of sratified shear layers). In the absence of subvisual cirrus, a 4 km detection range is maintained. A table depicting the warning time in seconds with respect to the aircraft speed and instrument range (in kilometers) is presented.

Martinson, Robert J.↗
NASA NTRS1999

Interdisciplinary Determination of Ice Sheet Accumulation Patterns: Combined Atmospheric Modeling and Field and Remote Sensing Studies

This research is focusing on two related areas that are fundamental to the NASA PARCA (Program for Arctic Regional Climate Assessment) program. The primary research area is the determination of the amount, rate, and timing of accumulation at distributed sites in the dry snow zone of Greenland and evaluation of these results in light of accumulation modeling results. The secondary research area is the calibration of the isotope "thermometer" at these ice sheet sites as well as the determination of long-term temperature trends in Greenland.

Shuman, C. A.↗
NASA NTRS2001

The Role of Remote Sensing Displays in Earth Climate and Planetary Atmospheric Research

The communities of scientists who study the Earth's climate and the atmospheres of the other planets barely overlap, but the types of questions they pose and the resulting implications for the use and interpretation of remote sensing data sets have much in common. Both seek to determine the characteristic behavior of three-dimensional fluids that also evolve in time. Climate researchers want to know how and why the general patterns that define our climate today might be different in the next century. Planetary scientists try to understand why circulation patterns and clouds on Mars, Venus, or Jupiter are different from those on Earth. Both disciplines must aggregate large amounts of data covering long time periods and several altitudes to have a representative picture of the rapidly changing atmosphere they are studying. This emphasis separates climate scientists from weather forecasters, who focus at any one time on a limited number of images. Likewise, it separates planetary atmosphere researchers from planetary geologists, who rely primarily on single images (or mosaics of images covering the globe) to study two-dimensional planetary surfaces that are mostly static over the duration of a spacecraft mission yet reveal dynamic processes acting over thousands to millions of years. Remote sensing displays are usually two-dimensional projections that capture an atmosphere at an instant in time. How scientists manipulate and display such data, how they interpret what they see, and how they thereby understand the physical processes that cause what they see, are the challenges I discuss in this chapter. I begin by discussing differences in how novices and experts in the field relate displays of data to the real world. This leads to a discussion of the use and abuse of image enhancement and color in remote sensing displays. I then show some examples of techniques used by scientists in climate and planetary research to both convey information and design research strategies using remote sensing displays.

DelGenio, Anthony D.↗
NASA NTRS2022

Optimal Estimation Framework for Ocean Color Atmospheric Correction and Pixel-level Uncertainty Quantification

Ocean color remote sensing requires compensation for atmospheric scattering and absorption (aerosol, Rayleigh, and trace gases), referred to as atmospheric correction (AC). AC allows inference of parameters such as spectrally resolved remote sensing reflectance ( R rs )(λ) ; sr 1 ) at the ocean surface from the top-of-atmosphere reflectance. Often, the uncertainty of this process is not fully explored. Bayesian inference techniques provide a simultaneous AC and uncertainty assessment via a full posterior distribution of the relevant variables, given the prior distribution of those variables and the radiative transfer (RT) likelihood function. Given uncertainties in the algorithm inputs, the Bayesian framework enables better constraints on the AC process by using the complete spectral information compared to traditional approaches that use only a subset of bands for AC. This paper investigates a Bayesian inference research method (Optimal Estimation, OE) for ocean color AC by simultaneously retrieving atmospheric and ocean properties using all visible and near-infrared spectral bands. The OE algorithm analytically approximates the posterior distribution of parameters based on normality assumptions and provides a potentially viable operational algorithm with a reduced computational expense. We developed a Neural Network (NN) RT forward model look-up-table-based emulator to increase algorithm efficiency further and thus speed up the likelihood computations. We then applied the OE algorithm to synthetic data and observations from the MODerate resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua spacecraft. We compared the R rs )(λ) retrieval and its uncertainty estimates from the OE method with in-situ validation data from the SeaWiFS Bio-optical Archive and Storage System (SeaBASS) and Aerosol Robotic Network Ocean Color (AERONET-OC) datasets. The OE algorithm improved R rs )(λ) estimates relative to the NASA standard operational algorithm by improving all statistical metrics at 443, 555, and 667 nm. Unphysical negative R rs )(λ) , which often appear in complex water conditions, was reduced by a factor of 3. The OE-derived pixel-level R rs )(λ) uncertainty estimates were also assessed relative to in-situ data and were shown to have skill.

Atmospheric correction↗
NASA NTRS1996

Empirical Line Parameters of NH(sub 3) from 4791 to 5294 cm(sup -1)

To support remote sensing of planetary atmospheres at 2??laboratory spectra of NH(sub 3) andf enriched (sup 14)NH(sub 3) and (sup 15)NH(sub 3) were recorded at 0.011 cm(sup -1) resolution with the McMath Fourier transform spectrometer (FTS) located at...

NH3 remote sensing planetary atmospheric study↗
NASA NTRS1975

On remote sounding of the upper atmosphere of Venus

Some of the possibilities for remote sensing of the upper atmosphere of Venus from an orbiting spacecraft are studied quantitatively. Temperature sounding over a wide vertical range, from the main cloud top near 60 km altitude to the nanobar level near 160 km, is shown to be feasible. Techniques which deconvolve the cloud structure from the temperature profile measurements are examined. Humidity measurements by simple radiometry are feasible for column abundances greater than or equal to 10 precipitable micrometers. The information content of limb radiance measurements, in different wavelengths and for various viewing geometries, is also analyzed.

Houghton, J. T.↗
NASA NTRS2020

Revised and extended benchmark results for Rayleigh scattering of sunlight in spherical atmospheres

While most of traditional Earth-atmosphere satellite remote sensing relies on radiative transfer in the plane parallel geometry, effects of sphericity are important at high sun and view zenith angles. Broad understanding of these effects is limited and, contrary to the plane-parallel case, finding accurate numerical results to test spherical RT codes is not easy. This paper aims to partially fill in this gap. Using the full-spherical RT code MYSTIC (Monte Carlo), and the plane-parallel RT code VLIDORT (discrete ordinates) corrected for atmospheric sphericity in the single and multiple scattering, we reproduced with better accuracy and extended the benchmark results by Adams & Kattawar [1978].

spherical atmospheres↗