We thank L. Pan, F. Sassi, G. Branstator, R. Saravanan, and G. Kiladis and two anonymous reviewers for constructive comments on this paper. The National Center for Atmospheric Research (NCAR) is operated by the University Corporation for Atmospheric Research under the sponsorship of the National Science Foundation. A. Gettelman was supported at NCAR by the Advanced Study Program, the Atmospheric Chemistry Division, and the Climate and Global Dynamics Division.
Atticks, M. G., , and G. D. Robinson, 1983: Some features of the structure of the tropical tropopause. Quart. J. Roy. Meteor. Soc, 109 , 295–308.
Brewer, A. W., 1949: Evidence for a world circulation provided by the measurements of helium and water vapor distribution in the stratosphere. Quart. J. Roy. Meteor. Soc, 75 , 351–363.
Chandra, S., , J. R. Ziemke, , W. Min, , and W. G. Read, 1998: Effects of 1997–1998 El Niño on tropospheric ozone and water vapor. Geophys. Res. Lett, 25 , 3867–3870.
de F. Forster, P. M., , and K. P. Shine, 1999: Stratospheric water vapour changes as a possible contributor to observed stratospheric cooling. Geophys. Res. Lett, 26 , 3309–3312.
Deser, C., , and J. M. Wallace, 1990: Large-scale atmospheric circulation features associated with warm and cold episodes in the tropical Pacific. J. Climate, 3 , 1254–1281.
Folkins, I., , M. Loewenstein, , J. Podolske, , S. J. Oltmans, , and M. Proffitt, 1999: A barrier to vertical mixing at 14 km in the Tropics: Evidence from ozonesondes and aircraft measurements. J. Geophys. Res, 104 , . (D18),. 22095–22102.
Gage, K. S., , and G. C. Reid, 1987: Longitudinal variations in tropical tropopause properties in relation to tropical convection and El Niño–Southern Oscillation events. J. Geophys. Res, 92 , . (C13),. 14197–14203.
Gettelman, A., , A. R. Douglass, , and J. R. Holton, 2000: Simulations of water vapor in the upper troposphere and lower stratosphere. J. Geophys. Res, 105 , 9003–9023.
Giorgetta, M. A., , and L. Bengtsson, 1999: Potential role of the quasi-biennial oscillation in the stratosphere–troposphere exchange as found in water vapor in general circulation model experiments. J. Geophys. Res, 104 , (D6),. 6003–6019.
Harries, J. E., and Coauthors. . 1996: Validation of measurements of water vapour from the Halogen Occultation Experiment (HALOE). J. Geophys. Res, 101 , 10205–10216.
Holton, J. R., , P. H. Haynes, , A. R. Douglass, , R. B. Rood, , and L. Pfister, 1995: Stratosphere–troposphere exchange. Rev. Geophys, 33 , 403–439.
Jackson, D. R., , S. J. Driscoll, , E. J. Highwood, , J. E. Harries, , and J. M. Russell III, 1998: Troposphere to stratosphere transport at low latitudes as studied using HALOE observations of water vapour 1992–1997. Quart. J. Roy. Meteor. Soc, 124 , 169–192.
Kiehl, J. T., , J. J. Hack, , G. B. Bonhan, , B. A. Boville, , B. P. Briegleb, , D. L. Williamson, , and P. J. Rasch, 1996: Description of the NCAR community climate model (CCM3). National Center for Atmospheric Research Tech. Rep. 420, 152 pp.
Kiladis, G. N., , K. H. Straub, , G. C. Reid, , and K. S. Gage, 2001: Aspects of interannual and intraseasonal variability of the tropopause and lower stratosphere. Quart. J. Roy. Meteor. Soc., in press.
Lorenz, E. N., 1956: Empirical orthogonal functions and statistical weather prediction. Dept. of Meteorology, Massachusettes Institute of Technology Tech. Rep. 1, 48 pp.
Massie, S., , P. Lowe, , X. X. Tie, , M. Hervig, , G. Thomas, , and J. M. Russell III, 2000: The effect of the 1997 El Niño on the distribution of upper tropospheric cirrus. J. Geophys. Res, 105 , . (D18),. 22725–22741.
McCormack, J. P., , R. Fu, , and W. G. Read, 2000: The influence of convective outflow on water vapor mixing ratios in the tropical upper troposphere: An analysis based on UARS MLS measurements. Geophys. Res. Lett, 27 , 525–528.
Michelsen, H. A., , F. W. Irion, , G. L. Manney, , G. C. Toon, , and M. R. Gunson, 2000: Features and trends in ATMOS version 3 water vapor and methane measurements. J. Geophys. Res, 105 , 22713–22724.
Mote, P. W., and Coauthors. . 1996: An atmospheric tape recorder: The imprint of tropical tropopause temperatures on stratospheric water vapor. J. Geophys. Res, 101 , . (D2),. 3989–4006.
Newell, R. E., , Y. Zhu, , E. V. Browell, , W. G. Read, , and J. W. Waters, 1996: Walker circulation and tropical upper tropospheric water vapor. J. Geophys. Res, 101 , . (D1),. 1961–1974.
Oltmans, S. J., , H. Vömel, , D. J. Hofmann, , K. H. Rosenlof, , and D. Kley, 2000: The increase in stratospheric water vapor from balloon-borne, frostpoint hygrometer measurements at Washington, D.C. and Boulder, Colorado. Geophys. Res. Lett, 27 , 3453–3456.
Oort, A. H., , and J. J. Yienger, 1996: Observed interannual variability in the Hadley circulation and its connection to ENSO. J. Climate, 9 , 2751–2767.
Randel, W. J., , F. Wu, , and D. J. Gaffen, 2000: Interannual variability of the tropical tropopause derived from radiosonde data and NCEP reanalyses. J. Geophys. Res, 105 , . (D12),. 15509–15523.
Randel, W. J., , A. Gettelman, , F. Wu, , J. M. Russell III, , J. Zawodny, , and S. Oltmans, 2001: The seasonal variation of water vapour in the lowest stratosphere observed in HALOE data. J. Geophys. Res., in press.
Read, W. G., , J. W. Waters, , D. A. Flower, , L. Froidevaux, , R. F. Jarnot, , D. L. Hartmann, , R. S. Harwood, , and R. B. Rood, 1995: Upper tropospheric water vapor from UARS MLS. Bull. Amer. Meteor. Soc, 76 , 2381–2389.
Reid, G. C., , and K. S. Gage, 1985: Interannual variations in the height of the tropical tropopause. J. Geophys. Res, 90 , . (D3),. 5629–5635.
Reid, G. C., , and K. S. Gage, 1996: The tropical tropopause over the western Pacific: Wave driving, convection, and the annual cycle. J. Geophys. Res, 101 , . (D16),. 21233–21241.
Russell, J. M. I. I. I., . and Coauthors. . 1993: The halogen occultation experiment. J. Geophys. Res, 98 , . (D6),. 10777–10797.
Salby, M. L., , and R. R. Garcia, 1987: Transient response to localized episodic heating in the Tropics. Part I: Excitation and short-time near-field behavior. J. Atmos. Sci, 44 , 458–498.
Sardeshmukh, P. D., , and B. J. Hoskins, 1985: Vorticity balances in the Tropics during the 1982–83 El Niño–Southern Oscillation event. Quart. J. Roy. Meteor. Soc, 111 , 261–278.
Sardeshmukh, P. D., , and B. J. Hoskins, 1988: The generation of global rotational flow by steady idealized tropical divergence. J. Atmos. Sci, 45 , 1228–1251.
Seidel, D. J., , R. J. Ross, , J. K. Angell, , and G. C. Reid, 2001: Climatological characteristics of the tropical tropopause as revealed by radiosondes. J. Geophys. Res, 106 , 7857–7878.
SPARC, 2000: SPARC Assessment of water vapor in the upper troposphere and lower stratosphere. Stratospheric Processes and Their Role in Climate, WMO/TD-1043, 312 pp.
Vömel, H., , S. Oltmans, , D. Kley, , and P. J. Crutzen, 1995: New evidence for the stratospheric dehydration mechanism in the equatorial Pacific. Geophys. Res. Lett, 22 , 3235–3238.
Webster, P. J., 1983: Large-scale structure of the tropical atmosphere. Large-Scale Dynamical Processes in the Atmosphere, B. Hoskins and R. Pearce, Eds., Academic Press, 235–275.
Webster, P. J., , V. O. Magana, , T. N. Palmer, , J. Shukla, , R. A. Thomas, , M. Yanai, , and T. Yasunari, 1998: Monsoons: Processes, predictability and the prospects for prediction. J. Geophys. Res, 103 , . (C7),. 14451–14510.
Yulaeva, E., , and J. M. Wallace, 1994: The signature of ENSO in global temperature and precipitation fields derived from the microwave sounding unit. J. Climate, 7 , 1719–1736.
Zhou, X., , M. A. Geller, , and M. Zhang, 2001: Tropical cold point tropopause characteristics derived from ECMWF reanalyses and soundings. J. Climate, 14 , 1823–1838.