• Andrews, D. G., J. R. Holton, and C. B. Leovy, 1987: Middle Atmosphere Dynamics. Academic Press, 21–112.

  • Bills, R. E., and C. S. Gardner, 1993: Lidar observations of the mesopause region temperature structure at Urbana. J. Geophys. Res.,98, 1011–1021.

  • ——, ——, and C. Y. She, 1991: Narrowband lidar technique for sodium temperature and Doppler wind observations of the upper atmosphere. Opt. Eng.,30, 13–21.

  • Dao, P. D., R. Farley, X. Tao, and C. S. Gardner, 1995: Lidar observations of the temperature profile between 25 and 103 km: Evidence of strong tidal perturbations. Geophys. Res. Lett.,22, 2825–2828,.

  • Fritts, D., and T. van Zandt, 1993: Spectral estimates of gravity wave energy and momentum fluxes: Energy dissipation, acceleration, and constraints. J. Atmos. Sci.,50, 3685–3694.

  • Garcia, R. R., and S. Solomon, 1985: The effect of breaking gravity waves on the dynamics and chemical composition of the mesosphere and lower thermosphere. J. Geophys. Res.,90, 3850–3868.

  • Gardner, C. S., and W. Yang, 1998: Measurements of the dynamical cooling rate associated with the vertical transport of heat by dissipating gravity waves in the mesopause region at the Starfire Optical Range, New Mexico. J. Geophys. Res.,103, 16 909–16 926.

  • Gavrilov, N. M., and R. G. Roble, 1994: The effect of gravity waves on the global mean temperature and composition structure of the upper atmosphere. J. Geophys. Res.,99, 25 773–25 780.

  • Hauchecorne, A., M. L. Chanin, and R. Wilson, 1987: Mesospheric temperature inversion and gravity wave breaking. Geophys. Res. Lett.,14, 935–937.

  • Leblanc, T., and A. Hauchecorne, 1997: Recent observations of mesospheric temperature inversions. J. Geophys. Res.,102, 19 471–19 482.

  • ——, I. S. McDermid, P. Keckhut, A. Hauchecorne, C. Y. She, and D. A. Krueger, 1998: Temperature climatology of the middle atmosphere from long-term lidar measurements at middle and low latitudes. J. Geophys. Res.,103, 17 191–17 204.

  • Lubken, F. J., 1997: Seasonal variation of turbulent energy dissipation rates at high latitudes as determined by in-situ measurements of neutral density fluctuations. J. Geophys. Res.,102, 13 441–13 456.

  • ——, W. Hillert, G. Lehmacher, and U. von Zahn, 1993: Experiments revealing small impact of turbulence on the energy budget of the mesosphere and lower thermosphere. J. Geophys. Res.,98, 20 369–20 384.

  • McLandress, C., 1998: On the importance of gravity waves in the middle atmosphere and their parameterization in general circulation models. J. Atmos. Solar Terr. Phys.,60, 1357–1383.

  • Meriwether, J. W., and M. G. Mlynczak, 1995: Is chemical heating a major cause of the mesosphere inversion layer? J. Geophys. Res.,100, 1379–1387.

  • ——, X. Gao, V. Wickwar, T. Wilkerson, K. Beissner, S. Collins, and M. Hagan, 1998: Observed coupling of the mesospheric inversion layer to the thermal tidal structure. Geophys. Res. Lett.,25, 1479–1482.

  • Mlynczak, M. G., and S. Solomon, 1991: Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species. Geophys. Res. Lett.,18, 37–40.

  • ——, and ——, 1993: A detailed evaluation of the heating efficiency in the middle atmosphere. J. Geophys. Res.,98, 10 517–10 541.

  • Papen, G. C., W. M. Pfenninger, and D. M. Simonich, 1995: Sensitivity analysis of Na narrowband wind-temperature lidar systems. Appl. Opt.,34, 480–498.

  • Plane, J. M. C., C. S. Gardner, J. R. Yu, C. Y. She, R. R. Garcia, and H. C. Pumphrey, 1998: The mesospheric Na layer at 40°N: Modeling and observations. J. Geophys. Res,104, 3773–3788.

  • Reise, M., D. Offermann, and G. Brasseur, 1994: Energy released by recombination of atomic oxygen related species at mesopause heights. J. Geophys. Res.,99, 14 585–14 594.

  • Roble, R. G., 1995: Energetics of the mesosphere and thermosphere. The Upper Mesosphere and Lower Thermosphere: A Review of Experiment and Theory, Geophys. Monogr., No. 87, Amer. Geophys. Union, 1–22.

  • ——, and R. E. Dickinson, 1989: How will changes in carbon dioxide and methane modify the mean structure of the mesosphere and thermosphere? Geophys. Res. Lett.,16, 1441–1444.

  • Rodgers, C. D., F. W. Taylor, A. H. Muggeridge, M. Lopez-Puertas, and M. A. Lopez-Valverde, 1992: Local thermodynamic equilibrium of carbon dioxide in the upper atmosphere. Geophys. Res. Lett.,19, 589–592.

  • Senft, D. C., G. C. Papen, C. S. Gardner, J. R. Yu, D. A. Krueger, and C. Y. She, 1994: Seasonal variations of the thermal structure of the mesopause region at Urbana, IL (40°N, 88°W) and Ft. Collins, CO (41°N, 105°W). Geophys. Res. Lett.,21, 821–824.

  • She, C. Y., and U. von Zahn, 1998: Concept of a two-level mesopause:Support through new lidar observations. J. Geophys. Res.,103, 5855–5863.

  • ——, J. R. Yu, H. Latifi, and R. E. Bills, 1992: High-spectral-resolution lidar for mesospheric sodium temperature measurements. Appl. Opt.,31, 2095–2106.

  • ——, ——, and H. Chen, 1993: Observed thermal structure of a midlatitude mesopause. Geophys. Res. Lett.,20, 567–570.

  • ——, ——, D. A. Krueger, R. Roble, P. Keckhut, A. Hauchecorne, and M. L. Chanin, 1995: Vertical structure of the midlatitude temperature from stratosphere to mesosphere (30–105 km). Geophys. Res. Lett.,22, 377–380.

  • Shimazaki, T., 1985: Minor Constituents in the Middle Atmosphere. Terra Scientific, 289–305.

  • States, R. J., and C. S. Gardner, 1998: Influence of the diurnal tide and thermospheric heat sources on the formation of mesospheric temperature inversion layers. Geophys. Res. Lett.,25, 1483–1486.

  • ——, and ——, 2000: Thermal structure of the mesopause region (80–105 km) at 40°N latitude. Part II: Diurnal variations. J. Atmos. Sci.,57, 78–92.

  • Thomas, G. E., J. J. Olivero, E. J. Jensen, W. Schroeder, and O. B. Toon, 1989: Relation between increasing methane and the presence of ice clouds in the mesosphere. Nature,338, 490–492.

  • von Zahn, U., J. Hoffner, V. Eska, and M. Alpers, 1996: The mesopause altitude: Only two distinctive levels worldwide? Geophys. Res. Lett.,23, 3231–3234.

  • Walterscheid, R. L., 1981: Dynamical cooling induced by dissipating internal gravity waves. Geophys. Res. Lett.,8, 1235–1238.

  • Wehrbein, W. M., and C. B. Leovy, 1982: An accurate radiative heating and cooling algorithm for use in a dynamical model of the middle atmosphere. J. Atmos. Sci.,39, 1532–1544.

  • Weinstock, J., 1983: Heat flux induced by gravity waves. Geophys. Res. Lett.,10, 165–167.

  • Yu, J. R., R. J. States, S. J. Franke, C. S. Gardner, and M. E. Hagan, 1997: Observations of tidal temperature and wind perturbations in the mesopause region above Urbana, IL (40°N, 88°W). Geophys. Res. Lett.,24, 1207–1210.

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Thermal Structure of the Mesopause Region (80–105 km) at 40°N Latitude. Part I: Seasonal Variations

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  • 1 Department of Electrical and Computer Engineering, University of Illinois, Urbana–Champaign, Urbana, Illinois
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Abstract

Sodium wind/temperature lidar measurements taken throughout the diurnal and annual cycles at Urbana, Illinois (40°N, 88°W), from February 1996 through January 1998 are used to characterize the seasonal variations of the mesospheric temperature structure between 80 and 105 km. By averaging data over several weeks and over the complete diurnal cycle, the significant effects of gravity waves, tides, and planetary waves are surpressed. The observed mean annual temperature structure is largely consistent with the assumption of radiative equilibrium between direct solar UV heating and radiative cooling by IR emission. Large seasonal variations of the mean thermal structure are observed. Below 91 km, there is strong adiabatic cooling in summer caused by the mean upward velocities associated with the diabatic circulation system. The maximum amplitude of the annual variation is 9.7 K at approximately 84 km. Above 98 km, increased UV absorption by O2 during summer drives an annual oscillation in this region with an amplitude of approximately 5 K. These two phenomena determine the seasonal variation of the mesopause altitude. The annual variation in solar UV heating in the lower thermosphere induces a modest 5-km peak to peak annual variation in the mesopause altitude. The mesopause is near 101 km in winter and ∼96 km in late summer. However, the summer cooling below 91 km is strong enough to define the minimum temperature, causing the mesopause altitude to fall to ∼87 km from about 7 May to about 15 July (∼70 days). The mesopause thickness, defined here as the altitude range where the temperature is within 5 K of the minimum, increases dramatically from approximately 7 km in winter to over 16 km in summer. Significant biases can occur in some parameters calculated from nighttime-only observations. The inversion layers that persist between 85 and 96 km in nighttime temperature profiles are virtually eliminated when data are averaged over the complete diurnal period. The strong annual temperature variation present around 84 km is overestimated by 40%, and the strong semiannual variation above 95 km is overestimated by as much as 150% when computed using only nighttime measurements. The low summer mesopause exists for a much longer period (∼126 days) in the nighttime observations. The mesopause temperature averaged over the annual cycle is 188 K compared to 190 K for the nighttime average. This bias is most pronounced during summertime, when the difference is 7 K.

Corresponding author address: C. S. Gardner, University of Illinois, Department of Electrical and Computer Engineering, 1308 W. Main St., Urbana, IL 61801.

Email: cgardner@uiuc.edu

Abstract

Sodium wind/temperature lidar measurements taken throughout the diurnal and annual cycles at Urbana, Illinois (40°N, 88°W), from February 1996 through January 1998 are used to characterize the seasonal variations of the mesospheric temperature structure between 80 and 105 km. By averaging data over several weeks and over the complete diurnal cycle, the significant effects of gravity waves, tides, and planetary waves are surpressed. The observed mean annual temperature structure is largely consistent with the assumption of radiative equilibrium between direct solar UV heating and radiative cooling by IR emission. Large seasonal variations of the mean thermal structure are observed. Below 91 km, there is strong adiabatic cooling in summer caused by the mean upward velocities associated with the diabatic circulation system. The maximum amplitude of the annual variation is 9.7 K at approximately 84 km. Above 98 km, increased UV absorption by O2 during summer drives an annual oscillation in this region with an amplitude of approximately 5 K. These two phenomena determine the seasonal variation of the mesopause altitude. The annual variation in solar UV heating in the lower thermosphere induces a modest 5-km peak to peak annual variation in the mesopause altitude. The mesopause is near 101 km in winter and ∼96 km in late summer. However, the summer cooling below 91 km is strong enough to define the minimum temperature, causing the mesopause altitude to fall to ∼87 km from about 7 May to about 15 July (∼70 days). The mesopause thickness, defined here as the altitude range where the temperature is within 5 K of the minimum, increases dramatically from approximately 7 km in winter to over 16 km in summer. Significant biases can occur in some parameters calculated from nighttime-only observations. The inversion layers that persist between 85 and 96 km in nighttime temperature profiles are virtually eliminated when data are averaged over the complete diurnal period. The strong annual temperature variation present around 84 km is overestimated by 40%, and the strong semiannual variation above 95 km is overestimated by as much as 150% when computed using only nighttime measurements. The low summer mesopause exists for a much longer period (∼126 days) in the nighttime observations. The mesopause temperature averaged over the annual cycle is 188 K compared to 190 K for the nighttime average. This bias is most pronounced during summertime, when the difference is 7 K.

Corresponding author address: C. S. Gardner, University of Illinois, Department of Electrical and Computer Engineering, 1308 W. Main St., Urbana, IL 61801.

Email: cgardner@uiuc.edu

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