Ice nucleation and dehydration in the Tropical Tropopause Layer

Jensen E.J.; Diskin G.; Lawson R.P.Lance S.Bui T.P.Hlavka D.McGill M.Pfister L.Toon O.B.Gaog R.

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Ice nucleation and dehydration in the Tropical Tropopause Layer

机译：Ice nucleation and dehydration in the Tropical Tropopause Layer

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Optically thin cirrus near the tropical tropopause regulate the humidity of air entering the stratosphere, which in turn has a strong influence on the Earth's radiation budget and climate. Recent highaltitude, unmanned aircraft measurements provide evidence for two distinct classes of cirrus formed in the tropical tropopause region: (i) vertically extensive cirrus with low ice number concentrations, low extinctions, and large supersaturations (up to ~70) with respect to ice; and (ii) vertically thin cirrus layers with much higher ice concentrations that effectively deplete the vapor in excess of saturation. The persistent supersaturation in the former class of cirrus is consistent with the long time-scales (several hours or longer) for quenching of vapor in excess of saturation given the low ice concentrations and cold tropical tropopause temperatures. The low-concentration clouds are likely formed on a background population of insoluble particles with concentrations less than 100 L ~(-1) (often less than 20 L~(-1)), whereas the high ice concentration layers (with concentrations up to 10,000 L~(-1)) can only be produced by homogeneous freezing of an abundant population of aqueous aerosols. These measurements, along with past high-altitude aircraft measurements, indicate that the low-concentration cirrus occur frequently in the tropical tropopause region, whereas the high-concentration cirrus occur infrequently. The predominance of the low-concentration clouds means cirrus near the tropical tropopause may typically allow entry of air into the stratosphere with as much as ~1.7 times the ice saturation mixing ratio.

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《Proceedings of the National Academy of Sciences of the United States of America》 |2013年第6期|2041-2046|共6页
作者
Jensen E.J.; Diskin G.; Lawson R.P.Lance S.Bui T.P.Hlavka D.McGill M.Pfister L.Toon O.B.Gaog R.;
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作者单位

National Aeronautics and Space Administration (NASA), Ames Research Center, Moffett Field, CA 94035, United States;

NASA Langley Research Center, Hampton, VA 23681, United States;

SPEC, Inc., Boulder, CO 80301, United StatesScience Systems and Applications, Inc., Lanham, MD 20706, United StatesNASA Goddard Space Flight Center, Greenbelt, MD 20771, United StatesDepartment of Atmospheric and Oceanic Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, CO 80302, United StatesChemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States;

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收录信息美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
原文格式 PDF
正文语种英语
中图分类自然科学总论;
关键词
ATTREX; Ice nuclei;

Ice nucleation and dehydration in the Tropical Tropopause Layer

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