Browsing by Author "Welton, Ellsworth"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Current and Future Perspectives of Aerosol Research at NASA Goddard Space Flight Center(AMS, 2014-10-01) Matsui, Toshi; Ichoku, Charles; Randles, Cynthia; Yuan, Tianle; Silva, Arlindo M. da; Colarco, Peter; Kim, Dongchul; Levy, Robert; Sayer, Andrew; Chin, Mian; Giles, David; Holben, Brent; Welton, Ellsworth; Eck, Thomas; Remer, LorraineAerosols are tiny atmospheric particles that are emitted from various natural and anthropogenic sources. They affect climate through direct and indirect interactions with solar and thermal radiation, clouds, and atmospheric circulation (Solomon et al. 2007). The launch of a variety of sophisticated satellite-based observing systems aboard the Terra, Aqua, Aura, SeaWiFS (see appendix for all acronym expansions), CALIPSO, and other satellites in the late 1990s to mid-2000s through the NASA EOS and other U.S. and non-U.S. programs ushered in a golden era in aerosol research. NASA has been a leader in providing global aerosol characterizations through observations from satellites, ground networks, and field campaigns, as well as from global and regional modeling. AeroCenter (http://aerocenter.gsfc.nasa.gov/), which was formed in 2002 to address the many facets of aerosol research in a collaborative manner, is an interdisciplinary union of researchers (~200 members) at NASA GSFC and other nearby institutions, including NOAA, several universities, and research laboratories. AeroCenter hosts a web-accessible regular seminar series and an annual meeting to present up-to-date aerosol research, including measurement techniques; remote sensing algorithms; modeling development; field campaigns; and aerosol interactions with radiation, clouds, precipitation, climate, biosphere, atmospheric chemistry, air quality, and human health. The 2013 annual meeting was held at the NASA GSFC Visitor Center on 31 May 2013, which coincided with the seventh anniversary of the passing of Yoram Kaufman, a modern pioneer in satellite-based aerosol science and the founder of AeroCenter. The central theme of this year's meeting was “current and future perspectives” of NASA's aerosol science and satellite missions.Item Model Planetary Boundary Layer Heights and Ground-Based, Airborne, and Satellite Lidar Data Provide New Insight on Air Quality(National Aeronautics and Space Administration) Lewis, Jasper; Welton, Ellsworth; McGrath-Spangler, Erica; Hegarty, JenniferItem Nocturnal Aerosol Optical Depth Measurements with a Small-Aperture Automated Photometer Using the Moon as a Light Source(AMS, 2011-10-01) Berkoff, Timothy A.; Sorokin, Mikail; Stone, Tom; Eck, Thomas; Hoff, Raymond; Welton, Ellsworth; Holben, BrentA method is described that enables the use of lunar irradiance to obtain nighttime aerosol optical depth (AOD) measurements using a small-aperture photometer. In this approach, the U.S. Geological Survey lunar calibration system was utilized to provide high-precision lunar exoatmospheric spectral irradiance predictions for a ground-based sensor location, and when combined with ground measurement viewing geometry, provided the column optical transmittance for retrievals of AOD. Automated multiwavelength lunar measurements were obtained using an unmodified Cimel-318 sunphotometer sensor to assess existing capabilities and enhancements needed for day/night operation in NASA’s Aerosol Robotic Network (AERONET). Results show that even existing photometers can provide the ability for retrievals of aerosol optical depths at night near full moon. With an additional photodetector signal-to-noise improvement of 10–100, routine use over the bright half of the lunar phase and a much wider range of wavelengths and conditions can be achieved. Although the lunar cycle is expected to limit the frequency of observations to 30%–40% compared to solar measurements, nevertheless this is an attractive extension of AERONET capabilities.