Polar mesospheric clouds observed by an iron Boltzmann lidar at Rothera (67.5°S, 68.0°W), Antarctica from 2002 to 2005: Properties and implications

Chu, Xinzhao; Espy, P. J.; Nott, G. J.; Diettrich, Jan C.; Gardner, Chester S.

doi:10.1029/2006jd007086

Cited by 50 publications

(99 citation statements)

References 42 publications

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“…The summer mesopause is colder and at a lower altitude in the NH summer compared to the SH summer (Huaman and Balsley 1999). Chu (2003) and Chu et al (2006) reported hemispheric differences of about 1 km in the altitude of polar mesospheric clouds (PMC) from lidar measurement. PMC altitudes are sensitive to temperature but also to other variable fields such as water vapor and vertical wind.…”

Section: Hemispheric Differencesmentioning

confidence: 99%

Global Dynamics of the MLT

2012

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The transition between the middle atmosphere and the thermosphere is known as the MLT region (for mesosphere and lower thermosphere). This area has some characteristics that set it apart from other regions of the atmosphere. Most notably, it is the altitude region with the lowest overall temperature and has the unique characteristic that the temperature is much lower in summer than in winter. The summer-to-winter-temperature gradient is the result of adiabatic cooling and warming associated with a vigorous circulation driven primarily by gravity waves. Tides and planetary waves also contribute to the circulation and to the large dynamical variability in the MLT. The past decade has seen much progress in describing and understanding the dynamics of the MLT and the interactions of dynamics with chemistry and radiation. This review describes recent observations and numerical modeling as they relate to understanding the dynamical processes that control the MLT and its variability. Results from the Whole Atmosphere Community Climate Model (WACCM), which is a comprehensive high-top general circulation model with interactive chemistry, are used to illustrate the dynamical processes. Selected observations from the Sounding the Atmosphere with Broadband Emission Radiometry (SABER) instrument are shown for comparison. WACCM simulations of MLT dynamics have some differences with observations. These differences and other questions and discrepancies described in recent papers point to a number of ongoing uncertainties about the MLT dynamical system.

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Section: Hemispheric Differencesmentioning

confidence: 99%

Global Dynamics of the MLT

2012

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“…5 and discussion) a higher NLC threshold removes dim NLC from the sample set, and as those are usually located at higher altitudes (anti-correlation of altitude and brightness, e.g. Chu et al, 2006), the NLC bottom altitude decreases with increasing brightness. Figure 6a shows how this correlation also effects accompanying PMSE.…”

Section: Pmse/nlc Bottom Altitudes In Common-volume Observationsmentioning

confidence: 99%

Coincident measurements of PMSE and NLC above ALOMAR (69° N, 16° E) by radar and lidar from 1999–2008

et al. 2011

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Abstract. Polar Mesosphere Summer Echoes (PMSE) and Noctilucent Clouds (NLC) have been routinely measured at the ALOMAR research facility in Northern Norway (69 • N, 16 • E) by lidar and radar, respectively. 2900 h of lidar measurements by the ALOMAR Rayleigh/Mie/Raman lidar were combined with almost 18 000 h of radar measurements by the ALWIN VHF radar, all taken during the years 1999 to 2008, to study simultaneous and common-volume observations of both phenomena. PMSE and NLC are known from both theory and observations to be positively linked. We quantify the occurrences of PMSE and/or NLC and relations in altitude, especially with respect to the lower layer boundaries. The PMSE occurrence rate is with 75.3% considerably higher than the NLC occurrence rate of 19.5%. For overlapping PMSE and NLC observations, we confirm the coincidence of the lower boundaries and find a standard deviation of 1.26 km, hinting at very fast sublimation rates. However, 10.1% of all NLC measurements occur without accompanying PMSE. Comparison of occurrence rates with solar zenith angle reveals that NLC without PMSE mostly occur around midnight indicating that the ice particles were not detected by the radar due to the reduced electron density.

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“…E.g. variations of PMC 15 occurrence frequency and brightness as function of local time have been observed in detail with lidar instruments (von Zahn et al, 1998;Chu et al, 2006;Fiedler et al, 2005Fiedler et al, , 2009Fiedler et al, , 2011Fiedler et al, , 2016Gerding et al, 2013). All these data show evidence of a large PMC brightness variability with local time.…”

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confidence: 53%

Local Time Dependence of Polar Mesospheric Clouds: A model study

Schmidt¹,

Baumgarten²,

Berger³

et al. 2017

Preprint

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Abstract.The Mesospheric Ice Microphysics And tranSport model (MIMAS) is used to study local time (LT) variations of polar mesospheric clouds (PMC) in the northern hemisphere during the period from 1979 to 2013. We investigate the tidal behavior of brightness, altitude and occurrence frequency and find a good agreement between model and lidar observations. Mean ice water content (IWC) values from MIMAS also match those from satellite observations. In the latitudinal band of 67.5

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Polar mesospheric clouds observed by an iron Boltzmann lidar at Rothera (67.5°S, 68.0°W), Antarctica from 2002 to 2005: Properties and implications

Cited by 50 publications

References 42 publications

Global Dynamics of the MLT

Global Dynamics of the MLT

Coincident measurements of PMSE and NLC above ALOMAR (69° N, 16° E) by radar and lidar from 1999–2008

Local Time Dependence of Polar Mesospheric Clouds: A model study

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