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Douglas H. K. Lee
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Douglas H. K. Lee
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Edward J. Zipser, Cynthia H. Twohy, Si-Chee Tsay, K. Lee Thornhill, Simone Tanelli, Robert Ross, T. N. Krishnamurti, Q. Ji, Gregory Jenkins, Syed Ismail, N. Christina Hsu, Robbie Hood, Gerald M. Heymsfield, Andrew Heymsfield, Jeffrey Halverson, H. Michael Goodman, Richard Ferrare, Jason P. Dunion, Michael Douglas, Robert Cifelli, Gao Chen, Edward V. Browell, and Bruce Anderson

In 2006, NASA led a field campaign to investigate the factors that control the fate of African easterly waves (AEWs) moving westward into the tropical Atlantic Ocean. Aircraft and surface-based equipment were based on Cape Verde's islands, helping to fill some of the data void between Africa and the Caribbean. Taking advantage of the international African Monsoon Multidisciplinary Analysis (AMMA) program over the continent, the NASA-AMMA (NAMMA) program used enhanced upstream data, whereas NOAA aircraft farther west in the Atlantic studied several of the storms downstream. Seven AEWs were studied during AMMA, with at least two becoming tropical cyclones. Some of the waves that did not develop while being sampled near Cape Verde likely intensified in the central Atlantic instead. NAMMA observations were able to distinguish between the large-scale wave structure and the smaller-scale vorticity maxima that often form within the waves. A special complication of the east Atlantic environment is the Saharan air layer (SAL), which frequently accompanies the AEWs and may introduce dry air and heavy aerosol loading into the convective storm systems in the AEWs. One of the main achievements of NAMMA was the acquisition of a database of remote sensing and in situ observations of the properties of the SAL, enabling dynamic models and satellite retrieval algorithms to be evaluated against high-quality real data. Ongoing research with this database will help determine how the SAL influences cloud microphysics and perhaps also tropical cyclogenesis, as well as the more general question of recognizing the properties of small-scale vorticity maxima within tropical waves that are more likely to become tropical cyclones.

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William L. Smith Jr., Christy Hansen, Anthony Bucholtz, Bruce E. Anderson, Matthew Beckley, Joseph G. Corbett, Richard I. Cullather, Keith M. Hines, Michelle Hofton, Seiji Kato, Dan Lubin, Richard H. Moore, Michal Segal Rosenhaimer, Jens Redemann, Sebastian Schmidt, Ryan Scott, Shi Song, John D. Barrick, J. Bryan Blair, David H. Bromwich, Colleen Brooks, Gao Chen, Helen Cornejo, Chelsea A. Corr, Seung-Hee Ham, A. Scott Kittelman, Scott Knappmiller, Samuel LeBlanc, Norman G. Loeb, Colin Miller, Louis Nguyen, Rabindra Palikonda, David Rabine, Elizabeth A. Reid, Jacqueline A. Richter-Menge, Peter Pilewskie, Yohei Shinozuka, Douglas Spangenberg, Paul Stackhouse, Patrick Taylor, K. Lee Thornhill, David van Gilst, and Edward Winstead

Abstract

The National Aeronautics and Space Administration (NASA)’s Arctic Radiation-IceBridge Sea and Ice Experiment (ARISE) acquired unique aircraft data on atmospheric radiation and sea ice properties during the critical late summer to autumn sea ice minimum and commencement of refreezing. The C-130 aircraft flew 15 missions over the Beaufort Sea between 4 and 24 September 2014. ARISE deployed a shortwave and longwave broadband radiometer (BBR) system from the Naval Research Laboratory; a Solar Spectral Flux Radiometer (SSFR) from the University of Colorado Boulder; the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) from the NASA Ames Research Center; cloud microprobes from the NASA Langley Research Center; and the Land, Vegetation and Ice Sensor (LVIS) laser altimeter system from the NASA Goddard Space Flight Center. These instruments sampled the radiant energy exchange between clouds and a variety of sea ice scenarios, including prior to and after refreezing began. The most critical and unique aspect of ARISE mission planning was to coordinate the flight tracks with NASA Cloud and the Earth’s Radiant Energy System (CERES) satellite sensor observations in such a way that satellite sensor angular dependence models and derived top-of-atmosphere fluxes could be validated against the aircraft data over large gridbox domains of order 100–200 km. This was accomplished over open ocean, over the marginal ice zone (MIZ), and over a region of heavy sea ice concentration, in cloudy and clear skies. ARISE data will be valuable to the community for providing better interpretation of satellite energy budget measurements in the Arctic and for process studies involving ice–cloud–atmosphere energy exchange during the sea ice transition period.

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