Seasonal variation of mesopause region wind shears, convective and dynamic instabilities above Fort Collins, CO: A statistical study

Sherman, James P.; She, C. Y.

doi:10.1016/j.jastp.2006.01.011

Cited by 17 publications

(25 citation statements)

References 27 publications

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“…Since we know that eddy diffusion occurs in the mesopause region it appears that strong dynamic instability must occur in order to overcome the static stability. There is in fact experimental evidence for the occurrence of dynamic instability from simultaneous winds and temperature measurements (Sherman and She, 2006). This suggests that the regions in which we see strong positive temperature gradients constitute turbulence-free zones, in which strong gradients in the mixing ratio of a minor constituent such as sodium can develop.…”

Section: Discussionmentioning

confidence: 67%

Mesopause region temperature structure observed by sodium resonance lidar

Clemesha

Simonich

Batista

2010

Journal of Atmospheric and Solar-Terrestrial Physics

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Section: Discussionmentioning

confidence: 67%

Mesopause region temperature structure observed by sodium resonance lidar

Clemesha

Simonich

Batista

2010

Journal of Atmospheric and Solar-Terrestrial Physics

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“…The adiabatic heating of displaced air volumes follows the dry adiabatic lapse rate, which is ∼9.5 K/km at mesopause heights [ Sherman and She , 2006]. Note that the dry adiabatic lapse rate is different from the environmental lapse rate quoted earlier.…”

Section: Discussionmentioning

confidence: 99%

Response of OH airglow temperatures to neutral air dynamics at 78°N, 16°E during the anomalous 2003–2004 winter

Dyrland¹,

Mulligan

Hall

et al. 2010

J. Geophys. Res.

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[1] Hydroxyl (OH) brightness temperatures from the mesopause region derived from temperature profiles from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite are compared with OH(6-2) rotational temperatures measured by spectrometer from Longyearbyen, Norway (78°N, 16°E), during the winter [2003][2004]. The two series correspond well, although the satellite measurements are higher by an average of 5.6 K ± 4.4 K. Reasons for this apparent bias are discussed. The two series give a near-continuous temperature record from this winter, making it possible to study the response of the temperatures to neutral air dynamics observed from meteor radar measurements of meridional and zonal wind. Vertical profiles of 1.6 mm OH volume emission rates from SABER reveal that the unusually high temperatures observed during January and February 2004 (240-250 K) correspond to a very low and bright OH layer. Significant linear correlations are found between meridional wind, OH temperature, and peak altitude. These data support the theory that the high temperatures result from an anomalously strong upper stratospheric vortex that confined air to the polar regions, coupled with meridional transport, which led to a strong downwelling of atomic oxygen-rich air, thereby lowering the altitude of the OH layer. The SABER data reveal that the re-formation of the OH layer at approximately 78 km altitude accounted for an increase in temperature of approximately 15 K, while the remaining temperature increase (20-35 K) is attributed to adiabatic heating and chemical heating from the exothermic reactions involved in producing the vibrationally excited OH.

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“…This suggests that convective instabilities are an important mechanism causing these “nodes.” Strictly speaking small positive Brunt‐Väisälä frequencies are still assumed to represent stable conditions. However, convective instabilities are expected only for few minutes [e.g., Sica and Thorsley , 1996; Sherman and She , 2006]. Because of our longer integration time of 1 hour convective instabilities are often smoothed out to small, but positives values of N 2 .…”

Section: Discussionmentioning

confidence: 99%

Lidar temperature measurements of gravity waves over Kühlungsborn (54°N) from 1 to 105 km: A winter‐summer comparison

et al. 2006

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[1] Since August 2002, temperature measurements from 1 to 105 km are performed at the Leibniz Institute of Atmospheric Physics in Kühlungsborn (54°N) with a combination of different lidars. Results from 14 nights in winter and 31 in summer are presented. Nightly mean profiles and fluctuations with a temporal and vertical resolution of 15 min and 1 km, respectively, are derived. In both seasons, wave energy propagates upward (phase propagates downward) with vertical phase speeds of À0.25 to À1.9 m/s. Phase speeds are generally larger in the mesosphere compared to the stratosphere because of decreasing static stability. Wave periods are found in the entire range of 1-8 hours (given by experimental constraints) with no preference for particular periods. The observed vertical wavelengths cover the entire instrumental range of 5-50 km, but the majority lies below 22 km in both seasons. In single nights, a few waves (up to three) dominate the wave spectrum and represent 45-65% of the entire variability. Wave amplitudes generally increase with altitude with a scale height of $18-22 km, i.e., less than expected (14 km) for propagation conserving momentum flux density. The gravity wave energy loss changes with altitude and is different in both seasons. Local fluctuation minima (''nodes'') are often observed, frequently colocated with convective instabilities. Temperature fluctuations are generally smaller in summer compared to winter (maximum values are 10 and 25 K, respectively). Applying gravity wave polarization relations to the mean winter and summer lidar temperature profiles, the difference of fluctuations is basically determined by the background conditions, especially at $60-80 km.

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Seasonal variation of mesopause region wind shears, convective and dynamic instabilities above Fort Collins, CO: A statistical study

Cited by 17 publications

References 27 publications

Mesopause region temperature structure observed by sodium resonance lidar

Mesopause region temperature structure observed by sodium resonance lidar

Response of OH airglow temperatures to neutral air dynamics at 78°N, 16°E during the anomalous 2003–2004 winter

Lidar temperature measurements of gravity waves over Kühlungsborn (54°N) from 1 to 105 km: A winter‐summer comparison

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