First detection of a noctilucent cloud by lidar

Hansen, G.; Serwazi, Marcus; Zahn, U. von

doi:10.1029/gl016i012p01445

Cited by 74 publications

(57 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, the very steep underside of the Na layer, and the gap of 2± 3 km between the Na and NLC layers (Fig. 6), are in excellent agreement with the lidar observations of Hansen et al (1989).…”

Section: Speciessupporting

confidence: 74%

The role of sodium bicarbonate in the nucleation of noctilucent clouds

Plane

2000

Annales Geophysicae

View full text Add to dashboard Cite

Abstract. It is proposed that a component of meteoric smoke, sodium bicarbonate (NaHCO 3 ), provides particularly eective condensation nuclei for noctilucent clouds. This assertion is based on three conditions being met. The ®rst is that NaHCO 3 is present at sucient concentration (%10 4 cm )3) in the upper mesosphere between 80 and 90 km. It is demonstrated that there is strong evidence for this based on recent laboratory measurements coupled with atmospheric modelling. The second condition is that the thermodynamics of NaHCO 3 (H 2 O) n cluster formation allow spontaneous nucleation to occur under mesospheric conditions at temperatures below 140 K. The Gibbs free energy changes for forming clusters with n = 1 and 2 were computed from quantum calculations using hybrid density functional/Hartree-Fock (B3LYP) theory and a large basis set with added polarization and diuse functions. The results were then extrapolated to higher n using an established dependence of the free energy on cluster size and the free energy for the sublimation of H 2 O to bulk ice. A 1-dimensional model of sodium chemistry was then employed to show that spontaneous nucleation to form ice particles (n >100) should occur between 84 and 89 km in the high-latitude summer mesosphere. The third condition is that other metallic components of meteoric smoke are less eective condensation nuclei, so that the total number of potential nuclei is small relative to the amount of available H 2 O. Quantum calculations indicate that this is probably the case for major constituents such as Fe(OH) 2 , FeO 3 and MgCO 3 .

show abstract

Section: Speciessupporting

confidence: 74%

The role of sodium bicarbonate in the nucleation of noctilucent clouds

Plane

2000

Annales Geophysicae

View full text Add to dashboard Cite

show abstract

“…The first observations of these silvery-white shining clouds date back to 1885 (Backhouse, 1885;Jesse, 1885;Leslie, 1885). The first measurements by lidar succeeded in 1989 (Hansen et al, 1989). Today, NLC are routinely measured by lidar technique (von Cossart et al,densities of 100 cm −3 (Hervig et al, 2009a) the large particles cause strong backscatter at optical wavelengths.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2011

View full text Add to dashboard Cite

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.

show abstract

“…Since the first detection of a noctilucent cloud by active optical remote sensing in 1989 (Hansen et al, 1989), the lidar technique plays an increasing role in NLC research, as it combines long-term observations with high sensitivity, precision, as well as reproducibility for determination of cloud parameters. From lidar observations it is possible to derive the size and shape of NLC particles, as well as the horizontal structure of cloud layers (von Cossart et al, 1999;Baumgarten et al, 2002a,b).…”

Section: Introductionmentioning

confidence: 99%

Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR

2005

View full text Add to dashboard Cite

Abstract. From 1997 were observed by lidar above the ALOMAR observatory in Northern Norway (69 • N) during a total of 1880 measurement hours. This data set contains NLC signatures for 640 h, covering all local times, even during the highest solar background conditions. After data limitation imposing a threshold value of 4×10 −10 m −1 sr −1 for the volume backscatter coefficient of the NLC particles, a measure for the cloud brightness, local time dependencies of the NLC occurrence frequency, altitude, and brightness were determined. On average, over the 7 years NLC occurred during the whole day and preferably in the early morning hours, with a maximum occurrence frequency of ∼40% between 4 and 7 LT. Splitting the data into weak and strong clouds yields almost identical amplitudes of diurnal and semidiurnal variations for the occurrence of weak clouds, whereas the strong clouds are dominated by the diurnal variation. NLC occurrence, altitude, as well as brightness, show a remarkable persistence concerning diurnal and semidiurnal variations from 1997 to 2003, suggesting that NLC above ALOMAR are significantly controlled by atmospheric tides. The observed mean anti-phase behavior between cloud altitude and brightness is attributed to a phase shift between the semidiurnal components by ∼ 6 h. Investigation of data for each individual year regarding the prevailing oscillation periods of the NLC parameters showed different phase relationships, leading to a complex variability in the cloud parameters.

show abstract

First detection of a noctilucent cloud by lidar

Cited by 74 publications

References 12 publications

The role of sodium bicarbonate in the nucleation of noctilucent clouds

The role of sodium bicarbonate in the nucleation of noctilucent clouds

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

Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR

Contact Info

Product

Resources

About