Institution
Langley Research Center
Facility•Hampton, Virginia, United States•
About: Langley Research Center is a facility organization based out in Hampton, Virginia, United States. It is known for research contribution in the topics: Mach number & Wind tunnel. The organization has 15945 authors who have published 37602 publications receiving 821623 citations. The organization is also known as: NASA Langley & NASA Langley Research Center.
Topics: Mach number, Wind tunnel, Aerodynamics, Boundary layer, Supersonic speed
Papers published on a yearly basis
Papers
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University of Colorado Boulder1, New Mexico Highlands University2, California Institute of Technology3, Norwegian Institute for Air Research4, Cooperative Institute for Research in Environmental Sciences5, Harvard University6, Chalmers University of Technology7, York University8, Langley Research Center9, Hampton University10
TL;DR: In this paper, the authors examined the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin, suggesting that energetic particle precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms and possibly persisting through January.
Abstract: Upper stratospheric enhancements in NOx (NO and NO2) were observed at high northern latitudes from March through at least July of 2004. Multi-satellite data analysis is used to examine the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin. The enhancements were a factor of 4 higher than nominal at some locations, and are unprecedented in the northern hemisphere since at least 1985. They were accompanied by reductions in O-3 of more than 60% in some cases. The analysis suggests that energetic particle precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms in late October 2003 and possibly persisting through January. Downward transport of the excess NOx, facilitated by unique meteorological conditions in 2004 that led to an unusually strong upper stratospheric vortex from late January through March, caused the enhancements.
277 citations
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TL;DR: A nonlinear control law which uses the feedback of the unit quaternion and the measured angular velocities is proposed and is shown to provide global asymptotic stability.
Abstract: This paper considers the problem of three-axis attitude stabilization of a rigid spacecraft. A nonlinear control law which uses the feedback of the unit quaternion and the measured angular velocities is proposed and is shown to provide global asymptotic stability. The control law does not require the knowledge of the system parameters and is, therefore, robust to modeling errors. The significance of the control law is that it can be used for large-angle maneuvers with guaranteed stability. >
276 citations
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TL;DR: In this paper, the authors report on two recently deployed NASA satellite systems (SAM II and SAGE) that are monitoring the stratospheric aerosol layer and obtain vertical aerosol and gaseous extinction profiles with 1 km vertical resolution.
Abstract: The potential climatological and environmental importance of the stratospheric aerosol layer has prompted great interest in measuring the properties of this aerosol. In this paper we report on two recently deployed NASA satellite systems (SAM II and SAGE) that are monitoring the stratospheric aerosol. The satellite orbits are such that nearly global coverage is obtained. The instruments mounted in the space-craft are sun photometers that measure solar intensity at specific wavelengths as it is moderated by atmospheric particulates and gases during each sunrise and sunset encountered by the satellites. The data obtained are “inverted” to yield vertical aerosol and gaseous (primarily ozone) extinction profiles with 1 km vertical resolution. Thus, latitudinal, longitudinal, and temporal variations in the aerosol layer can be evaluated. The satellite systems are being validated by a series of ground truth experiments using airborne and ground lidar, balloon-borne dustsondes, aircraft-mounted impactor...
276 citations
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TL;DR: In this paper, the authors proposed that Fe-mobilization can occur in mineral dust from East Asia by the incorporation of SO2 into the advecting dust plumes and subsequent acidification of the dust through heterogeneous SO2 oxidation.
Abstract: [1] For Fe contained in long-range transported aeolian dust to act as a micronutrient for oceanic phytoplankton it must be first dissolved or mobilized. We propose that Fe-mobilization can occur in mineral dust from East Asia by the incorporation of SO2 into the advecting dust plumes and subsequent acidification of the dust through heterogeneous SO2 oxidation. To test this hypothesis, we consider a dust plume that originated from the gobi-deserts and advected over the Pacific Ocean. Data collected over the Yellow Sea confirm that this plume contained high concentrations of dust and SO2. Significant gaseous HNO3 concentrations indicate that the dust particles were acidified (i.e., pH < 2). At these pH's, 1–2% of the Fe contained in a deliquescent mineral dust particle would be mobilized within 3–5 days. These results suggest a possible link between the rate of C-fixation in so-called High-Nitrate-Low-Chlorophyll regions of the Pacific Ocean and SO2 emissions from East Asia.
276 citations
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Harvard University1, Research Triangle Park2, Langley Research Center3, University of California, Berkeley4, Pennsylvania State University5, University of New Hampshire6, National Center for Atmospheric Research7, University of Colorado Boulder8, Earth System Research Laboratory9, Texas A&M University10, Ames Research Center11
TL;DR: In this article, the authors used observations from two aircraft during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of the regional sources, chemical evolution, and export of nitrogen oxides.
Abstract: We use observations from two aircraft during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of the regional sources, chemical evolution, and export of nitrogen oxides. The boundary layer NO(x) data provide top-down verification of a 50% decrease in power plant and industry NO(x) emissions over the eastern United States between 1999 and 2004. Observed 8-12 8 km NO(x) concentrations in ICARTT were 0.55 +/- 36 ppbv, much larger than in previous United States aircraft campaigns (ELCHEM, SUCCESS, SONEX). We show that regional lightning was the dominant source of this NO(x) and increased upper tropospheric ozone by 10 ppbv. Simulating the ICARTT upper tropospheric NO(x) observations with GEOS-Chem require a factor of 4 increase in the model NO(x) yield per flash (to 500 mol/flash). Observed OH concentrations were a factor of 2 lower than can be explained from current photochemical models, and if correct would imply a broader lightning influence in the upper troposphere than presently thought.An NO(y)-CO correlation analysis of the fraction f of North American NO(x) emissions vented to the free troposphere as NO(y) (sum of NO(x) and its oxidation products PAN and HNO3) s shows observed f=16+/-10 percent and modeled f=14 +/- 8 percent, consistent with previous studies. Export to the lower free troposphere is mostly HNO3 but at higher altitudes is mostly PAN. The model successfully simulates NO(y) export efficiency and speciation, supporting previous model estimates of a large U.S. contribution to tropospheric ozone through NO(x) and PAN export.
276 citations
Authors
Showing all 16015 results
Name | H-index | Papers | Citations |
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Daniel J. Jacob | 162 | 656 | 76530 |
Donald R. Blake | 118 | 727 | 49697 |
Veerabhadran Ramanathan | 100 | 301 | 47561 |
Raja Parasuraman | 91 | 402 | 41455 |
Robert W. Platt | 88 | 638 | 31918 |
James M. Russell | 87 | 691 | 29383 |
Daniel J. Inman | 83 | 918 | 37920 |
Antony Jameson | 79 | 474 | 31518 |
Ya-Ping Sun | 79 | 277 | 28722 |
Patrick M. Crill | 79 | 228 | 20850 |
Richard B. Miles | 78 | 759 | 25239 |
Patrick Minnis | 77 | 490 | 23403 |
Robert W. Talbot | 77 | 297 | 19783 |
Raphael T. Haftka | 76 | 773 | 28111 |
Jack E. Dibb | 75 | 344 | 18399 |