Langley Research Center

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.

Evolution of brown carbon in wildfire plumes

Abstract: Particulate brown carbon (BrC) in the atmosphere absorbs light at subvisible wavelengths and has poorly constrained but potentially large climate forcing impacts. BrC from biomass burning has virtually unknown lifecycle and atmospheric stability. Here, BrC emitted from intense wildfires was measured in plumes transported over 2 days from two main fires, during the 2013 NASA SEAC4RS mission. Concurrent measurements of organic aerosol (OA) and black carbon (BC) mass concentration, BC coating thickness, absorption Angstrom exponent, and OA oxidation state reveal that the initial BrC emitted from the fires was largely unstable. Using back trajectories to estimate the transport time indicates that BrC aerosol light absorption decayed in the plumes with a half-life of 9 to 15 h, measured over day and night. Although most BrC was lost within a day, possibly through chemical loss and/or evaporation, the remaining persistent fraction likely determines the background BrC levels most relevant for climate forcing.

Comparison of regional clear-sky albedos inferred from satellite-observations and model computations

Abstract: A comparison of model- and satellite-inferred clear sky top-of-atmosphere (TOA) albedos is presented. The clear sky albedos were inferred from GOES-2 observations for November 1978 over South America and most of North America and adjacent ocean regions. The model albedos were computed on a 1 deg X 1 deg latitude-longitude grid, allowing for variations in surface vegetation type, solar zenith angle, orography, and spectral absorption/scattering. Over the ocean areas, the observed and calculated TOA albedos agree within + or - 1 percent, while the albedos over land mostly agree within + or - 2 percent for the entire range of significant geographical variation of albedo from 13 percent over the Amazon Basin to 24 percent over mountains of western North America. Both the ocean and land agreements lie within the theoretical and observational uncertainties.

Stratospheric Aerosol And Gas Experiment II Instrument: A Functional Description

Abstract: Design and performance data are presented for the Strato-spheric Aerosol and Gas Experiment II (SAGE II) instrument, which has been developed for the Earth Radiation Budget Satellite (ERBS). SAGE II is designed to monitor globally the vertical distribution of stratospheric aerosols, ozone, water vapor, and nitrogen dioxide by measuring the ex-tinction of solar radiation through the earth's atmosphere during the ERBS observatory solar occultations. Solar radiation is reflected from a flat scanning mirror into a Cassegrain telescope, which forms a solar image on the entrance slit of a grating spectrometer. The SAGE II instan-taneous field of view is scanned along the vertical solar diameter by the elevation scan mirror. The entire optical system is contained within an azimuth gimbal that tracks the solar radiometric centroid during the data event. This spectrometer, with help from three interference filters, iso-lates seven spectral wavelengths ranging from 0.385 um to 1.02 um. All seven channels use silicon photodiode detectors operated in the photo-voltaic mode. Detector outputs are multiplexed into a serial data stream for readout by the ERBS telemetry system. Each output is sampled 64 times per second and digitized to 12 bit resolution. SAGE II is a third generation instrument, following the highly successful Stratospheric Aerosol Measurement II (SAM II) and SAGE programs.

Urban Air Mobility Airspace Integration Concepts and Considerations

Abstract: Urban Air Mobility (UAM) - defined as safe and efficient air traffic operations in a metropolitan area for manned aircraft and unmanned aircraft systems - is being researched and developed by industry, academia, and government. Significant resources have been invested toward cultivating an ecosystem for Urban Air Mobility that includes manufacturers of electric vertical takeoff and landing aircraft, builders of takeoff and landing areas, and researchers of the airspace integration concepts, technologies, and procedures needed to conduct Urban Air Mobility operations safely and efficiently alongside other airspace users. This paper provides high-level descriptions of both emergent and early expanded operational concepts for Urban Air Mobility that NASA is developing. The scope of this work is defined in terms of missions, aircraft, airspace, and hazards. Past and current Urban Air Mobility operations are also reviewed, and the considerations for the data exchange architecture and communication, navigation, and surveillance requirements are also discussed. This paper will serve as a starting point to develop a framework for NASA's Urban Air Mobility airspace integration research and development efforts with partners and stakeholders that could include fast-time simulations, human-in-the-loop (HITL) simulations, and flight demonstrations.

Surface Irradiances of Edition 4.0 Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Data Product

Abstract: The algorithm to produce the Clouds and the Earth’s Radiant Energy System (CERES) Edition 4.0 (Ed4) Energy Balanced and Filled (EBAF)-surface data product is explained. The algorithm forces...