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Tropical entrainment time scales inferred from stratospheric N_2O and CH_4 observations

Herman, R. L. and Scott, D. C. and Webster, C. R. and May, R. D. and Moyer, E. J. and Salawitch, R. J. and Yung, Y. L. and Toon, G. C. and Sen, B. and Margitan, J. J. and Rosenlof, K. H. and Michelsen, H. A. and Elkins, J. W. (1998) Tropical entrainment time scales inferred from stratospheric N_2O and CH_4 observations. Geophysical Research Letters, 25 (15). pp. 2781-2784. ISSN 0094-8276. doi:10.1029/98GL02109.

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Simultaneous in situ measurements of N_2O and CH_4 were made with a tunable diode laser spectrometer (ALIAS II) aboard the Observations from the Middle Stratosphere (OMS) balloon platform from New Mexico, Alaska, and Brazil during 1996 and 1997. We find different compact relationships of CH_4 with N_2O in the tropics and extra-tropics because mixing is slow between these regions. Transport into the extra-tropics from the tropics or the polar vortex leads to deviations from the normal compact relationship. We use measured N_2O and CH_4 and a simple model to quantify entrainment of mid-latitude stratospheric air into the tropics. The entrainment time scale is estimated to be 16 (+17, −8) months for altitudes between 20 and 28 km. The fraction of tropical air entrained from the extra-tropical stratosphere is 50% (+18%, −30%) at 20 km, increasing to 78% (+11%, −19%) at 28 km.

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Yung, Y. L.0000-0002-4263-2562
Toon, G. C.0000-0003-4174-7541
Alternate Title:Tropical entrainment time scales inferred from stratospheric N2O and CH4 observations
Additional Information:© 1998 American Geophysical Union. Received March 11, 1998; revised June 8, 1998; accepted June 15, 1998. We thank C. M. Volk, F. L. Moore, K. Minschwaner, and two anonymous reviewers for helpful comments, H. Vömel for temperature data, and A. E. Kulawik for computational assistance. We also thank W. H. Brune, G. J. Flesch, L. Kroll, M. Tuchscherer, J. Riccio, R. Howe, B. Wilson, J. Landeros, and the National Scientific Balloon Facility (NSBF) for assistance. Support for this work and the OMS balloon flights was provided by NASA's Upper Atmospheric Research Program and Atmospheric Effects of Aviation Project. H.A.M. was supported by NASA grant NAS1-96022. Part of the research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Division of Geological and Planetary Sciences, California Institute of Technology, Contribution 5762.
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NASA Upper Atmosphere Research ProgramUNSPECIFIED
NASA Atmospheric Effects of Aviation ProjectUNSPECIFIED
Issue or Number:15
Record Number:CaltechAUTHORS:20140819-085416821
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Official Citation:Herman, R. L., Scott, D. C., Webster, C. R., May, R. D., Moyer, E. J., Salawitch, R. J., . . . Elkins, J. W. (1998). Tropical entrainment time scales inferred from stratospheric N2O and CH4 observations. Geophysical Research Letters, 25(15), 2781-2784. doi: 10.1029/98gl02109
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48671
Deposited On:19 Aug 2014 18:40
Last Modified:10 Nov 2021 18:34

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