1,395 research outputs found
VROHI: Visibility Recovery for Outdoor Hazy Image in Scattering Media
© 2009-2012 IEEE. Additive haze model (AHM), due to its high simplicity, has a potential to increase the efficiency of the restoration procedure of images degraded by scattering media. However, AHM is designed for hazy remote sensing data and is not suitable to be used on outdoor images. In this paper, according to the low-frequency feature (LFC) of haze, AHM is modified via gamma correction technique to make it suitable for modeling outdoor images. Benefitting from the modified AHM (MAHM), a simple yet effective method called VROHI is proposed to enhance the visibility of an outdoor hazy image. In specific, a low complexity LFC extraction method is designed by utilizing characteristic of the discrete cosine transform. Subsequently, by constructing the linear function of unknown parameters and imposing the saturation prior on MAHM, the image dehazing problem can be derived into a global optimization function. Experiments reveal that the proposed VROHI is superior to the other state-of-the-art techniques in terms of both the processing efficiency and recovery quality
MODIS: Moderate-resolution imaging spectrometer. Earth observing system, volume 2B
The Moderate-Resolution Imaging Spectrometer (MODIS), as presently conceived, is a system of two imaging spectroradiometer components designed for the widest possible applicability to research tasks that require long-term (5 to 10 years), low-resolution (52 channels between 0.4 and 12.0 micrometers) data sets. The system described is preliminary and subject to scientific and technological review and modification, and it is anticipated that both will occur prior to selection of a final system configuration; however, the basic concept outlined is likely to remain unchanged
COrE (Cosmic Origins Explorer) A White Paper
COrE (Cosmic Origins Explorer) is a fourth-generation full-sky,
microwave-band satellite recently proposed to ESA within Cosmic Vision
2015-2025. COrE will provide maps of the microwave sky in polarization and
temperature in 15 frequency bands, ranging from 45 GHz to 795 GHz, with an
angular resolution ranging from 23 arcmin (45 GHz) and 1.3 arcmin (795 GHz) and
sensitivities roughly 10 to 30 times better than PLANCK (depending on the
frequency channel). The COrE mission will lead to breakthrough science in a
wide range of areas, ranging from primordial cosmology to galactic and
extragalactic science. COrE is designed to detect the primordial gravitational
waves generated during the epoch of cosmic inflation at more than
for . It will also measure the CMB gravitational lensing
deflection power spectrum to the cosmic variance limit on all linear scales,
allowing us to probe absolute neutrino masses better than laboratory
experiments and down to plausible values suggested by the neutrino oscillation
data. COrE will also search for primordial non-Gaussianity with significant
improvements over Planck in its ability to constrain the shape (and amplitude)
of non-Gaussianity. In the areas of galactic and extragalactic science, in its
highest frequency channels COrE will provide maps of the galactic polarized
dust emission allowing us to map the galactic magnetic field in areas of
diffuse emission not otherwise accessible to probe the initial conditions for
star formation. COrE will also map the galactic synchrotron emission thirty
times better than PLANCK. This White Paper reviews the COrE science program,
our simulations on foreground subtraction, and the proposed instrumental
configuration.Comment: 90 pages Latex 15 figures (revised 28 April 2011, references added,
minor errors corrected
Performance specifications for a meteorological satellite lidar Final report
Cirrus cloud cover observation capability and performance specifications for meteorological satellite lida
The pale orange dot : the spectrum and habitability of hazy Archean Earth
Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8–2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7–2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO2. Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets.Publisher PDFPeer reviewe
Mariner Mars 1969 final project report. Volume 3: Scientific investigations
Postflight analysis of Mariner l and 7 scientific data - Vol.
Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC
We derive tropospheric column BrO during the ARCTAS and ARCPAC field campaigns in spring 2008 using retrievals of total column BrO from the satellite UV nadir sensors OMI and GOME-2 using a radiative transfer model and stratospheric column BrO from a photochemical simulation. We conduct a comprehensive comparison of satellite-derived tropospheric BrO column to aircraft in-situ observations of BrO and related species. The aircraft profiles reveal that tropospheric BrO, when present during April 2008, was distributed over a broad range of altitudes rather than being confined to the planetary boundary layer (PBL). Perturbations to the total column resulting from tropospheric BrO are the same magnitude as perturbations due to longitudinal variations in the stratospheric component, so proper accounting of the stratospheric signal is essential for accurate determination of satellite-derived tropospheric BrO. We find reasonably good agreement between satellite-derived tropospheric BrO and columns found using aircraft in-situ BrO profiles, particularly when satellite radiances were obtained over bright surfaces (albedo \u3e0.7), for solar zenith angl
Dust on Mars
Topics addressed include: sedimentary debris; mineralogy; Martian dust cycles; Mariner 9 mission; Viking observations; Mars Observer; atmospheric circulation; aeolian features; aerosols; and landslides.sponsored by the Lunar and Planetary Institute, National Aeronautics and Space Administration.edited by Steven LeePhysical properties of aeolian features in the Elysium-Amazonis region of Mars / Zimbelman, J.R. -- Martian atmoshperic dust processes over three years as inferred from Lander meteorology measurements / Tillman, J.E. -- Dust in the spring season polar atmospheres: A north-south comparison / Paige, D.A. -- Martian miniature slope failures, Mutch Memorial Station / Moore, H.J. -- Infrared opacity of dust in the Mars atmosphere / Martin, T.
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