scholarly journals The red-sky enigma over Svalbard in December 2002

2005 ◽  
Vol 23 (5) ◽  
pp. 1593-1602
Author(s):  
F. Sigernes ◽  
N. Lloyd ◽  
D. A. Lorentzen ◽  
R. Neuber ◽  
U.-P. Hoppe ◽  
...  
Keyword(s):  
Scattered Light ◽  
Atmospheric Composition ◽  
The Sun ◽  
Polar Stratospheric Clouds ◽  
Atmospheric Sciences ◽  
Composition And Structure ◽  
History Of Geophysics ◽  
History Of ◽  
Instruments And Techniques ◽  
Stratospheric Clouds

Abstract. On 6 December 2002, during winter darkness, an extraordinary event occurred in the sky, as viewed from Longyearbyen (78° N, 15° E), Svalbard, Norway. At 07:30 UT the southeast sky was surprisingly lit up in a deep red colour. The light increased in intensity and spread out across the sky, and at 10:00 UT the illumination was observed to reach the zenith. The event died out at about 12:30 UT. Spectral measurements from the Auroral Station in Adventdalen confirm that the light was scattered sunlight. Even though the Sun was between 11.8 and 14.6deg below the horizon during the event, the measured intensities of scattered light on the southern horizon from the scanning photometers coincided with the rise and setting of the Sun. Calculations of actual heights, including refraction and atmospheric screening, indicate that the event most likely was scattered solar light from a target below the horizon. This is also confirmed by the OSIRIS instrument on board the Odin satellite. The deduced height profile indicates that the scattering target is located 18–23km up in the stratosphere at a latitude close to 73–75° N, southeast of Longyearbyen. The temperatures in this region were found to be low enough for Polar Stratospheric Clouds (PSC) to be formed. The target was also identified as PSC by the LIDAR systems at the Koldewey Station in Ny-Ålesund (79° N, 12° E). The event was most likely caused by solar illuminated type II Polar Stratospheric Clouds that scattered light towards Svalbard. Two types of scenarios are presented to explain how light is scattered. Keywords. Atmospheric composition and structure (Transmissions and scattering of radiation; Middle atmospherecomposition and chemistry; Instruments and techniques) – History of geophysics (Atmospheric Sciences; The red-sky phenomena)

scholarly journals <i>Letter to the Editor</i>On the use of the sunspot number for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations

2005 ◽  
Vol 23 (5) ◽  
pp. 1959-1961
Author(s):  
Keyword(s):  
Sunspot Number ◽  
Upper Atmosphere ◽  
Atmospheric Composition ◽  
Short Contribution ◽  
Middle Latitudes ◽  
Composition And Structure ◽  
History Of Geophysics ◽  
History Of ◽  
The Mean ◽  
Auroral Phenomena

Abstract. In this short contribution the use of different sunspot numbers for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations realised by Schröder et al. (2004) is analysed. Moreover, some comments are made on the relationships between mean annual visual observations of the auroras at middle latitudes of Europe and the mean annual sunspot number during 1780–1829. Keywords. Atmospheric composition and structure (Airglow and aurora) – Magnetospheric physics (Auroral phenomena, solar wind-magnetosphere interactions) – History of geophysics (Solar-planetary relationship)

scholarly journals World first complex optical instrumental observations of aurora in the Arctic in 1899−1900

2005 ◽  
Vol 23 (5) ◽  
pp. 1523-1531 ◽  
Author(s):  
S. A. Chernouss ◽  
G. V. Starkov ◽  
L. S. Yevlashin
Keyword(s):  
Winter Season ◽  
Auroral Oval ◽  
Point Of View ◽  
The Arctic ◽  
Atmospheric Sciences ◽  
Instrumental Observations ◽  
History Of Geophysics ◽  
History Of ◽  
Instruments And Techniques ◽  
Auroral Emissions

Abstract. This report presents data and analysis of visual, photographic and auroral spectral data, obtained by the Russian astronomer J. Sykora from the Russian-Swedish expedition to Spitsbergen during the 1899–1900 winter season, which are historically significant for auroral studies. These data seem to be the first instrumental observations of auroral spectra in the Arctic and some of the emissions discovered have world priority. The second known photos in the world of aurora from the Arctic and undoubtedly the first ones for geomagnetic latitudes of about 75° in the Spitsbergen Archipelago were obtained. The results of the expedition are discussed from a modern point of view and compared with our knowledge of the 21st century. A description of the equipment and methods that were used by Russian astronomers is presented. Both photographic and spectral devices using registration by photographic plates were used, along with special methods of their development and enhancement. Some statistical analysis was done on the basis of the expedition reports and diaries. This analysis shows that by using Sykora's data it was possible to discover the auroral oval or instantaneous auroral distribution over the polar region. Analysis of photographic samples and sketches of the aurora demonstrate typical auroral form outlines as they are described today. Spectral plates exposed for several hours to auroral lights revealed not only the main auroral emissions, which were well-known at that time, but several other unidentified weak emissions, which were rediscovered and interpreted years later. Keywords. History of geophysics (Atmospheric sciences, instruments and techniques)

scholarly journals Occurrence of polar stratospheric clouds at Kiruna

1999 ◽  
Vol 17 (11) ◽  
pp. 1457-1462 ◽  
Author(s):  
C.-F. Enell ◽  
Å. Steen ◽  
T. Wagner ◽  
U. Frieß ◽  
K. Pfeilsticker ◽  
...  
Keyword(s):  
Weather Conditions ◽  
Data Availability ◽  
Atmospheric Composition ◽  
Mountain Range ◽  
Polar Stratospheric Clouds ◽  
Mesoscale Meteorology ◽  
Optical Instruments ◽  
Composition And Structure ◽  
Stratospheric Clouds ◽  
Frequent Presence

Abstract. Polar stratospheric clouds (PSCs) are often observed in the Kiruna region in northern Sweden, east of the Scandinavian mountain range, during wintertime. PSC occurrence can be detected by ground-based optical instruments. Most of these require clear tropospheric weather. By applying the zenith-sky colour index technique, which works under most weather conditions, the data availability can be extended. The observations suggest that PSC events, especially of type II (water PSCs) may indeed more common than predicted by synoptic models, which is expected because of the frequent presence of mountain-induced leewaves. However, it will be of importance to increase the density of independent observations.Key words. Atmospheric composition and structure (aerosols and particles · cloud physics and chemistry) · Meteorology and atmospheric dynamics (mesoscale meteorology)

scholarly journals Case study of the development of polar stratospheric clouds using bistatic imaging

2003 ◽  
Vol 21 (8) ◽  
pp. 1869-1878
Author(s):  
C.-F. Enell ◽  
U. Brändström ◽  
B. Gustavsson ◽  
S. Kirkwood ◽  
K. Stebel ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Polar Vortex ◽  
Three Dimensions ◽  
Atmospheric Composition ◽  
Polar Stratospheric Clouds ◽  
Composition And Structure ◽  
Threshold Temperatures ◽  
Stratospheric Clouds ◽  
Wave Induced

Abstract. The formation of polar stratospheric clouds (PSCs) is closely related to wave activity on different scales since waves propagating into the stratosphere perturb the temperature profile. We present here a case study of the development of visible PSCs (mother-of-pearl clouds), appearing at the polar vortex edge on 9 January 1997, under-taken by means of ground-based cameras. It is shown that the presence of stratospheric clouds may be detected semi-automatically and that short-term dynamics such as altitude variations can be tracked in three dimensions. The PSC field showed distinct features separated by approximately 20 km, which implies wave-induced temperature variations on that scale. The wave-induced characteristics were further emphasised by the fact that the PSCs moved within a sloping spatial surface. The appearance of visible mother-of-pearl clouds seems to be related to leewave-induced cooling of air masses, where the synoptic temperature has been close to (but not necessarily below) the threshold temperatures for PSC condensation.Key words. Atmospheric composition and structure (aerosols and particles) – Meteorology and atmospheric dynamics (middle atmosphere dynamics; instruments and techniques)

scholarly journals Doppler temperatures from O(<sup>1</sup>D) airglow in the daytime thermosphere as observed by the Wind Imaging Interferometer (WINDII) on the UARS satellite

2002 ◽  
Vol 20 (2) ◽  
pp. 203-212 ◽  
Author(s):  
C. Lathuillère ◽  
W. A. Gault ◽  
B. Lamballais ◽  
Y. J. Rochon ◽  
B. H. Solheim
Keyword(s):  
Atmospheric Composition ◽  
Large Set ◽  
Temperature Variations ◽  
Data Processing Software ◽  
Imaging Interferometer ◽  
Composition And Structure ◽  
Instruments And Techniques ◽  
The Mean ◽  
First Time ◽  
Good Agreement

Abstract. From 1992 to 1997, the WINDII interferometer on board the UARS satellite acquired a large set of thermospheric data from the O(1D) and O(1S) airglows. We report here for the first time on daytime O(1D) Doppler temperatures obtained with version 5.11 of the WINDII data processing software. Using a statistical analysis of the temperatures independently measured by the two WINDII fields of view, we estimate that the temperature variations larger than 40 K can be considered as geophysical. Comparisons of WINDII temperatures measured during magnetically quiet days with temperatures obtained by the MSIS-90 and DTM-94 thermospheric models show a 100 K bias. We demonstrate, however, that the modeled temperature variations represent very well the mean temperature variation observed by WINDII over 4 years. We also show that the observed latitudinal/local time variation is in very good agreement with the two empirical models. Finally, the temperature variations during a magnetically disturbed day are found to be qualitatively well represented in form by the models, but largely underestimated. The presence of non-thermal atoms and instrument related issues are discussed as possible explanations for the 100 K bias between the WINDII Doppler temperatures and the empirical models.Key words. Atmospheric composition and structure (air-glow and aurora; pressure, density and temperature; instruments and techniques)

scholarly journals An explanation for some fallstreak clouds

2002 ◽  
Vol 20 (5) ◽  
pp. 711-715 ◽  
Author(s):  
R. M. Worthington
Keyword(s):  
Radar Data ◽  
Atmospheric Dynamics ◽  
Atmospheric Composition ◽  
Cloud Physics ◽  
Mountain Wave ◽  
Mountain Waves ◽  
Meteorology And Atmospheric Dynamics ◽  
Composition And Structure ◽  
Waves And Tides ◽  
Stratospheric Clouds

Abstract. Fallstreak cirrus clouds are associated with super-saturated air, together with waves, instabilities and/or turbulence; however, their precise cause is usually uncertain. This paper uses already-published satellite, radiosonde and radar data, reanalysed to study some large fallstreaks which had been previously overlooked. The fallstreaks – up to 60 km long with a parent cloud 20 km wide – are caused by lifting and/or turbulence from a mountain wave, rather than, for example, Kelvin-Helmholtz instabilities. If turbulent breaking of mountain waves affects ice particle formation, this may be relevant for the seeder-feeder effect on orographic rain, and the efficiency of mountain-wave polar stratospheric clouds for ozone depletion.Key words. Meteorology and atmospheric dynamics (turbulence; waves and tides) – Atmospheric composition and structure (cloud physics and chemistry)

scholarly journals Mesospheric temperatures from observations of the hydroxyl (6–2) emission above Davis, Antarctica: A comparison of rotational and Doppler measurements

2001 ◽  
Vol 19 (3) ◽  
pp. 359-365 ◽  
Author(s):  
J. L. Innis ◽  
F. A. Phillips ◽  
G. B. Burns ◽  
P. A. Greet ◽  
W. J. R. French ◽  
...  
Keyword(s):  
The Other ◽  
Atmospheric Composition ◽  
Austral Winter ◽  
Data Set ◽  
Composition And Structure ◽  
Fabry Perot ◽  
Instruments And Techniques ◽  
The Mean ◽  
Observational Errors ◽  
Line Widths

Abstract. We present observations of the hydroxyl (6–2) airglow lines from ~ 87 km altitude obtained at Davis station, Antarctica, in the austral winter of 1999. Nine nights of observations were made of the P-branch near λ840 nm with a Czerny-Turner scanning spectrometer (CTS); at the same time, high-resolution Fabry-Perot Spectrometer (FPS) spectra were collected of the Q1(1) doublet at λ834 nm. Rotational temperatures were determined from the CTS observations, while Doppler temperatures were derived from the line-widths of the FPS Q1(1) spectra. Absolute temperatures determined by these methods are uncertain by ~ 2 and ~ 20 K, respectively. For the comparison we set the value of the reflective finesse of the FPS at λ834 nm so the mean FPS temperature from one night of simultaneous data was equal to that from the CTS, and then looked at the measured variations in each data set for the other eight nights. Both instruments show the upper mesosphere temperature to vary in a similar manner to within the observational errors of the measurements, implying an equivalence of the rotational and Doppler temperatures. We believe that this is the first published simultaneous, same-site, comparison of rotational and Doppler temperatures from the OH emission. Key words. Atmospheric composition and structure (airglow and aurora; pressure density and temperature; instruments and techniques)

10 years of Polar Stratospheric Clouds lidar measurements at the French antarctic station Dumont d’Urville

2020 ◽  
Author(s):  
Florent Tencé ◽  
Julien Jumelet ◽  
Alain Sarkissian ◽  
Slimane Bekki ◽  
Philippe Keckhut
Keyword(s):  
Stratospheric Ozone ◽  
Atmospheric Composition ◽  
Polar Regions ◽  
Primary Role ◽  
Atmospheric Conditions ◽  
Polar Stratospheric Clouds ◽  
Ice Clouds ◽  
Yearly Average ◽  
Lidar Measurements ◽  
Stratospheric Clouds

&lt;p&gt;&lt;span&gt;Polar Stratospheric Clouds (PSCs) play a primary role in polar stratospheric ozone depletion processes. &lt;/span&gt;&lt;span&gt;Aside from recent improvements in both spaceborne PSCs monitoring as well as investigations on PSCs microphysics and modeling, there are still uncertainties associated to solid particle formation and their denitrification potential. In that regard, groundbased instruments deliver detailed and valuable measurements that complement the global spaceborne coverage.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Operated since 1989 at the French antarctic station Dumont d&amp;#8217;Urville (DDU) in the frame of the international Network for the Detection of Atmospheric Composition Change (NDACC), the Rayleigh/Mie/Raman lidar provides over the years a solid dataset to feed both process and classification studies, by monitoring cloud and aerosol occurrences in the upper troposphere and lower stratosphere. Located on antarctic shore (66&amp;#176;S - 140&amp;#176;E), the station has a privileged access to polar vortex dynamics. Measurements are weather-dependent with a yearly average of 130 nights of monitoring. Expected PSC formation temperatures are used to evaluate the whole PSC season occurrences.&lt;/p&gt;&lt;p&gt;We hereby present a consolidated dataset from 10 years of lidar measurements using the 532nm backscatter ratio, the aerosol depolarisation and local atmospheric conditions to help in building an aerosol/cloud classification. Using the different PSC classes and associated optical properties thresholds established in the recent PSC CALIOP classification, we build a picture of the 2007-2019 events, from march to october.&lt;/p&gt;&lt;p&gt;Overall, the DDU PSC pattern is very consistent with expected typical temperature controlled microphysical calculations. Outside of background sulfate aerosols and anomalies related to volcanic activity (like in 2015), Supercooled Ternary Solution (STS) particles are the most observed particle type, closely followed by Nitric Acid Trihydrate (NAT). ICE clouds are less but regularly observed. ICE clouds also have to be cleary separated from cirrus clouds, raising the issue of accurate dynamics tropopause calculations.&lt;/p&gt;&lt;p&gt;&lt;span&gt;Validation of the spaceborne measurements as well as multiple signatures of volcanic or even biomass originated aerosol plumes strengthens the need for groundbased monitoring &lt;/span&gt;&lt;span&gt;especially in polar regions where instrumental facilities remain sparse.&lt;/span&gt;&lt;/p&gt;

scholarly journals High resolution 2-D maps of OI 630.0 nm thermospheric dayglow from equatorial latitudes

1998 ◽  
Vol 16 (8) ◽  
pp. 997-1006
Author(s):  
D. Pallam Raju ◽  
R. Sridharan
Keyword(s):  
High Resolution ◽  
Gravity Waves ◽  
Large Scale ◽  
Equatorial Electrojet ◽  
Equatorial Ionosphere ◽  
Atmospheric Composition ◽  
Scale Feature ◽  
Equatorial Ionization Anomaly ◽  
Composition And Structure ◽  
Instruments And Techniques

Abstract. The first-ever high resolution 2-D maps of OI 630.0 nm dayglow obtained from equatorial latitudes clearly reveal the movement as a large-scale feature of the equatorial ionization anomaly (EIA). These also show the presence of wave-like features classified as gravity waves presumably originating at the crest of the EIA, similar to the equatorial electrojet acting as a source of these waves. These results are presented and discussed.Key words. Atmospheric composition and structure (Airglow and aurora) · Ionosphere (Equatorial ionosphere; Instruments and techniques).

scholarly journals Seasonal variations of O<sub>2</sub> atmospheric and OH(6−2) airglowand temperature at mid-latitudes from SATI observations

2004 ◽  
Vol 22 (3) ◽  
pp. 819-828 ◽  
Author(s):  
M. J. López-González ◽  
E. Rodríguez ◽  
R. H. Wiens ◽  
G. G. Shepherd ◽  
S. Sargoytchev ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Key Words ◽  
Sierra Nevada ◽  
Seasonal Variations ◽  
Annual Variation ◽  
Emission Rate ◽  
Atmospheric Composition ◽  
Emission Rates ◽  
Composition And Structure ◽  
Instruments And Techniques

Abstract. More than 3 years of airglow observations with a Spectral Airglow Temperature Imager (SATI) installed at the Sierra Nevada Observatory (37.06°N, 3.38°W) at 2900m height have been analyzed. Values of the column emission rate and vertically averaged temperature of the O2 atmospheric (0–1) band and of the OH Meinel (6–2) band from 1998 to 2002 have been presented. From these observations a clear seasonal variation of both emission rates and rotational temperatures is inferred at this latitude. It is found that the annual variation of the temperatures is larger than the semi-annual variation, while for the emission rates the amplitudes are comparable. Key words. Atmospheric composition and structure (airglow and aurora; pressure density and temperature; instruments and techniques)

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