The effect of atmospheric screening on the visible border of noctilucent clouds

Taylor, Michael J.; Hapgood, M. A.; Simmons, D. A. R.

doi:10.1016/0021-9169(84)90121-1

Cited by 14 publications

(6 citation statements)

References 8 publications

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“…At that time, no technique was available to measure densities or temperatures in that part of the atmosphere. Many altitude observations of NLCs have been performed since then, however, most of the time without a simultaneous measurement of the atmospheric temperature profile at mesopause altitudes [see, e.g.,Witt, 1962;Taylor and Hapgood, 1984]. The first temperattire measurements around the mesopause in conjunction with NLC observations were performed in the early 1960s over Kronog•rd, Sweden (60øN) [Witt, 1968] and over Point Barrow, Alaska (71øN)[Theon e!…”

mentioning

confidence: 90%

Noctilucent clouds and the thermal structure near the Arctic mesopause in summer

Lübken¹,

Fricke²,

Langer³

1996

J. Geophys. Res.

102

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In the summers of 1993 and 1994 a series of meteorological rockets and sounding rockets were launched from the Andøya Rocket Range (69°N) during the SCALE and ECHO campaigns in order to investigate the state of the mesosphere and lower thermosphere (SCALE = “SCAttering Layer Experiment”; ECHO indicates that radar and lidar echoes are investigated). At the same location a Rayleigh lidar was operational during these campaigns and searched for enhanced backscatter signals from the upper mesosphere indicative of the presence of noctilucent clouds (NLC). In five cases the lidar detected a NLC and the atmospheric temperature profile was obtained simultaneously by in situ techniques. A literature survey shows that there are only three more cases of unambiguous and simultaneous observations of NLC temperature and altitude. The temperature profiles obtained during SCALE and ECHO are as expected for the high‐latitude summer season: The mean mesopause temperature is 135 K at an altitude of 87.5 km. The variability of the temperatures is smaller above ∼84 km altitude than below. The mean temperature below the mesopause shows a remarkable repeatability ever since the first measurements 30 years ago; at the lower edge of the NLC heights (82 km) it is again and again observed to be in the range 150 ± 2 K and the variability within each data set is only a few Kelvins. Such an “equithermal submesopause” in summer puts a serious constraint on any model prediction of secular changes of temperatures in the upper mesosphere. The mean altitude of the NLCs as determined from our lidar measurements is 83.1 km which is surprisingly close to the very first height determinations more than 100 years ago. It is conceivable that this repeatability in altitude reflects a similar repeatability of the thermal structure. There is no apparent correlation between the conditions at the mesopause and the occurrence of NLCs at lower altitudes. The physical reason behind this is presumably related to the fact that the wind direction changes at ∼87 km height, which implies that the air masses observed above the rocket site near mesopause altitudes have been advected from different locations than those at NLC heights. The NLCs are always located below the mesopause, and the temperature in the NLC layer is observed to be lower than 154 K. Our results are compatible with the idea that NLCs consist of ice particles which start to nucleate around the mesopause, sediment to lower altitudes while growing, become observable by the lidar and/or by the naked eye, and finally evaporate once they approach the higher temperatures around 82 km.

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mentioning

confidence: 90%

Noctilucent clouds and the thermal structure near the Arctic mesopause in summer

Lübken¹,

Fricke²,

Langer³

1996

J. Geophys. Res.

102

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“…Subsequent ground-based and rocket-borne measurements have determined their remarkably consistent altitude, occurring in the upper mesosphere at a mean height of $83 km (e.g. Jesse, 1896;Strö rmer, 1933;Paton, 1964;Grahn and Witt, 1971;Witt et al, 1971;Bjorn et al, 1985;Taylor et al, 1984, Gadsden and Taylor, 1994, von Zahn et al, 1998Chu et al, 2001;Collins et al, 2003;Thayer et al, 2003;Fiedler et al, 2005;Gerding et al, 2007). NLC are seasonal, appearing during the summer months in close association with the observed rapid decrease in mesopause temperatures that result from strong upwelling in the summer polar region in response to the gravity wave-driven mean meridional circulation (e.g.…”

Section: Introductionmentioning

confidence: 97%

“…Witt, 1962;Grahn and Witt, 1971;Taylor et al, 1984). The clouds are conspicuous by their silvery blue color and are usually characterized by a variety of structures including gravity wave bands and billows (e.g.…”

Section: Introductionmentioning

confidence: 99%

Coordinated optical and radar image measurements of noctilucent clouds and polar mesospheric summer echoes

Taylor

Zhao

Pautet

et al. 2009

Journal of Atmospheric and Solar-Terrestrial Physics

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“…They are frequently characterized by a variety of spatially periodic wave structures. Indeed, observations over the past ~120 years have established a standard NLC classification with large‐scale “bands” and small‐scale “billows” as two of the primary categories for describing the clouds' appearance (Fogle & Haurwitz, ; Gadsden & Parviainen, ; Gadsden & Schrȍder, ; Taylor et al, ; Witt, ).…”

Section: Introductionmentioning

confidence: 99%

“…Ground-based optical, rocket-borne, and, more recently, active lidar soundings of these clouds have provided a wealth of information on their evolution, particle size, wave dynamics, and altitude structure essential for quantifying their variability (Chu et al, 2003;Rapp et al, 2002;Semeter & Mendillo, 1997). They have also established the remarkably consistent and stable altitude of the NLCs in the upper mesosphere over the past century, occurring at a mean height of 83 ± 2.5 km (Baumgarten et al, 2009;Collins et al, 2009;Chu et al, 2004;Gadsden & Taylor, 1994;Gerding et al, 2007;Jesse, 1896;Paton, 1964;Stoȑmer, 1933;Taylor et al, 1984;Thayer et al, 2003;von Zahn et al, 1998). However, most of these measurements are from isolated sites and are naturally limited by the prevailing weather conditions (Gadsden & Schroder, 1989).…”

Section: Introductionmentioning

confidence: 99%

Investigating Gravity Waves in Polar Mesospheric Clouds Using Tomographic Reconstructions of AIM Satellite Imagery

et al. 2018

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This research presents the first application of tomographic techniques for investigating gravity wave structures in polar mesospheric clouds (PMCs) imaged by the Cloud Imaging and Particle Size instrument on the NASA AIM satellite. Albedo data comprising consecutive PMC scenes were used to tomographically reconstruct a 3‐D layer using the Partially Constrained Algebraic Reconstruction Technique algorithm and a previously developed “fanning” technique. For this pilot study, a large region (760 × 148 km) of the PMC layer (altitude ~83 km) was sampled with a ~2 km horizontal resolution, and an intensity weighted centroid technique was developed to create novel 2‐D surface maps, characterizing the individual gravity waves as well as their altitude variability. Spectral analysis of seven selected wave events observed during the Northern Hemisphere 2007 PMC season exhibited dominant horizontal wavelengths of ~60–90 km, consistent with previous studies. These tomographic analyses have enabled a broad range of new investigations. For example, a clear spatial anticorrelation was observed between the PMC albedo and wave‐induced altitude changes, with higher‐albedo structures aligning well with wave troughs, while low‐intensity regions aligned with wave crests. This result appears to be consistent with current theories of PMC development in the mesopause region. This new tomographic imaging technique also provides valuable wave amplitude information enabling further mesospheric gravity wave investigations, including quantitative analysis of their hemispheric and interannual characteristics and variations.

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The effect of atmospheric screening on the visible border of noctilucent clouds

Cited by 14 publications

References 8 publications

Noctilucent clouds and the thermal structure near the Arctic mesopause in summer

Noctilucent clouds and the thermal structure near the Arctic mesopause in summer

Coordinated optical and radar image measurements of noctilucent clouds and polar mesospheric summer echoes

Investigating Gravity Waves in Polar Mesospheric Clouds Using Tomographic Reconstructions of AIM Satellite Imagery

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