Institution
Goddard Space Flight Center
Facility•Greenbelt, Maryland, United States•
About: Goddard Space Flight Center is a facility organization based out in Greenbelt, Maryland, United States. It is known for research contribution in the topics: Galaxy & Solar wind. The organization has 19058 authors who have published 63344 publications receiving 2786037 citations. The organization is also known as: GSFC & Space Flight Center.
Topics: Galaxy, Solar wind, Magnetosphere, Stars, Population
Papers published on a yearly basis
Papers
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TL;DR: An attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations to provide satellite retrieval of higher consistency, because the retrieval over each single pixel will be benefiting from coincident aerosol information from neighboring pixels.
Abstract: . The proposed development is an attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations. This optimization concept improves retrieval accuracy relying on the knowledge of measurement error distribution. Efficient application of such optimization requires pronounced data redundancy (excess of the measurements number over number of unknowns) that is not common in satellite observations. The POLDER imager on board the PARASOL micro-satellite registers spectral polarimetric characteristics of the reflected atmospheric radiation at up to 16 viewing directions over each observed pixel. The completeness of such observations is notably higher than for most currently operating passive satellite aerosol sensors. This provides an opportunity for profound utilization of statistical optimization principles in satellite data inversion. The proposed retrieval scheme is designed as statistically optimized multi-variable fitting of all available angular observations obtained by the POLDER sensor in the window spectral channels where absorption by gas is minimal. The total number of such observations by PARASOL always exceeds a hundred over each pixel and the statistical optimization concept promises to be efficient even if the algorithm retrieves several tens of aerosol parameters. Based on this idea, the proposed algorithm uses a large number of unknowns and is aimed at retrieval of extended set of parameters affecting measured radiation. The algorithm is designed to retrieve complete aerosol properties globally. Over land, the algorithm retrieves the parameters of underlying surface simultaneously with aerosol. In all situations, the approach is anticipated to achieve a robust retrieval of complete aerosol properties including information about aerosol particle sizes, shape, absorption and composition (refractive index). In order to achieve reliable retrieval from PARASOL observations even over very reflective desert surfaces, the algorithm was designed as simultaneous inversion of a large group of pixels within one or several images. Such multi-pixel retrieval regime takes advantage of known limitations on spatial and temporal variability in both aerosol and surface properties. Specifically the variations of the retrieved parameters horizontally from pixel-to-pixel and/or temporary from day-to-day are enforced to be smooth by additional a priori constraints. This concept is expected to provide satellite retrieval of higher consistency, because the retrieval over each single pixel will be benefiting from coincident aerosol information from neighboring pixels, as well, from the information about surface reflectance (over land) obtained in preceding and consequent observations over the same pixel. The paper provides in depth description of the proposed inversion concept, illustrates the algorithm performance by a series of numerical tests and presents the examples of preliminary retrieval results obtained from actual PARASOL observations. It should be noted that many aspects of the described algorithm design considerably benefited from experience accumulated in the preceding effort on developments of currently operating AERONET and PARASOL retrievals, as well as several core software components were inherited from those earlier algorithms.
463 citations
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École Polytechnique1, City College of New York2, Max Planck Society3, University of Wisconsin-Madison4, University of Illinois at Urbana–Champaign5, National Oceanic and Atmospheric Administration6, Langley Research Center7, Goddard Space Flight Center8, Rutherford Appleton Laboratory9, Centre national de la recherche scientifique10
TL;DR: The Global Energy and Water Cycle Experiment (GEWEX) Cloud Assessment as discussed by the authors provides the first coordinated intercomparison of publicly available, standard global cloud products (gridded monthly statistics) retrieved from measurements of multispectral imagers (some with multiangle view and polarization capabilities).
Abstract: Clouds cover about 70% of Earth's surface and play a dominant role in the energy and water cycle of our planet. Only satellite observations provide a continuous survey of the state of the atmosphere over the entire globe and across the wide range of spatial and temporal scales that compose weather and climate variability. Satellite cloud data records now exceed more than 25 years; however, climate data records must be compiled from different satellite datasets and can exhibit systematic biases. Questions therefore arise as to the accuracy and limitations of the various sensors and retrieval methods. The Global Energy and Water Cycle Experiment (GEWEX) Cloud Assessment, initiated in 2005 by the GEWEX Radiation Panel (GEWEX Data and Assessment Panel since 2011), provides the first coordinated intercomparison of publicly available, standard global cloud products (gridded monthly statistics) retrieved from measurements of multispectral imagers (some with multiangle view and polarization capabilities), IR soun...
463 citations
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TL;DR: In this article, the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board the Fermi observatory were used to observe the long gamma-ray burst, GRB 090902B.
Abstract: We report on the observation of the bright, long gamma-ray burst (GRB), GRB 090902B, by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board the Fermi observatory. ...
462 citations
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University of Maryland, College Park1, University of Alaska Fairbanks2, Max Planck Society3, Jet Propulsion Laboratory4, Goddard Space Flight Center5, University of Hawaii6, Purdue University7, University of Arizona8, Brown University9, Cornell University10, University of Provence11, Johns Hopkins University Applied Physics Laboratory12, University of Paris13
TL;DR: In situ observations show that comet Hartley 2 is an unusually hyperactive comet, and this nucleus is outgassing primarily because of CO2, which drags chunks of ice out of the nucleus.
Abstract: Understanding how comets work, i,e., what drives their activity, is crucial to using comets to study the early solar system. EPOXI flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus. taking both images and spectra. Unlike large, relatively inactive nuclei, this nncleus is outgassing primarily due to CO2, which drags chnnks of ice out of the nnclens. It also shows significant differences in the relative abundance of volatiles from various parts of the nucleus.
461 citations
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TL;DR: In this article, several currently available broadband parameterizations for longwave and shortwave radiation have been combined to produce a computationally fast radiation parameterization that is well suited for atmospheric circulation models.
Abstract: Several currently available broadband parameterizations for longwave and shortwave radiation have been combined to produce a computationally fast radiation parameterization that is well suited for atmospheric circulation models. The main features of the parameterization are the ability to include overlapping partly cloudy layers in the longwave, the use of a delta-Eddington technique to treat clouds in the shortwave, and a computational structure that is amenable to vectorization on supercomputers. Selected results of off-line one-dimensional computations using the code have been compared with more rigorous methods as part of an international intercomparison program and found to be quite accurate.
461 citations
Authors
Showing all 19247 results
Name | H-index | Papers | Citations |
---|---|---|---|
Anton M. Koekemoer | 168 | 1127 | 106796 |
Alexander S. Szalay | 166 | 936 | 145745 |
David W. Johnson | 160 | 2714 | 140778 |
Donald G. York | 160 | 681 | 156579 |
Takeo Kanade | 147 | 799 | 103237 |
Gillian R. Knapp | 145 | 460 | 121477 |
Olaf Reimer | 144 | 716 | 74359 |
R. A. Sunyaev | 141 | 848 | 107966 |
Christopher T. Russell | 137 | 2378 | 97268 |
Hui Li | 135 | 2982 | 105903 |
Neil Gehrels | 134 | 727 | 80804 |
Christopher B. Field | 133 | 408 | 88930 |
Igor V. Moskalenko | 132 | 542 | 58182 |
William T. Reach | 131 | 535 | 90496 |
Adam Burrows | 130 | 623 | 55483 |