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 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 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 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)

scholarly journals First observation of one noctilucent cloud by a twin lidar in two different directions

2002 ◽  
Vol 20 (11) ◽  
pp. 1863-1868 ◽  
Author(s):  
G. Baumgarten ◽  
F.-J. Lübken ◽  
K. H. Fricke
Keyword(s):  
Middle Atmosphere ◽  
Early Morning ◽  
Atmospheric Composition ◽  
Noctilucent Cloud ◽  
Particle Sedimentation ◽  
Composition And Structure ◽  
Cross Correlation Analysis ◽  
Wind Measurements ◽  
The Mean ◽  
Observation Period

Abstract. In the early morning hours of 14 July 1999, a noctilucent cloud (NLC) was observed simultaneously by the two branches of a twin lidar system located at the ALOMAR observatory in northern Norway (69° N). The telescopes of the two lidars were pointing vertical (L^) and off the zenith by 30° (L30°). The two lidars detected an enhancement in the altitude profile of backscattered light (relative to the molecular background) for more than 5 h, starting approximately at 01:00 UT. These measurements constitute the detection of one NLC by two lidars under different directions and allow for a detailed study of the morphology of the NLC layer. A cross-correlation analysis of the NLC signals demonstrates that the main structures seen by both lidars are practically identical. This implies that a temporal evolution of the microphysics within the NLC during its drift from one lidar beam to the other is negligible. From the time delay of the NLC structures, a drift velocity of 55–65 m/s is derived which agrees nicely with radar wind measurements. During the observation period, the mean NLC altitude decreases by ~0.5 km/h (=14 cm/s) at both observation volumes. Further-more, the NLC is consistently observed approximately 500 m lower in altitude at L30° compared to L^. Supplementing these data by observations from rocket-borne and ground-based instruments, we show that the general downward progression of the NLC layer through the night, as seen by both lidars, is caused by a combination of particle sedimentation by 4–5 cm/s and a downward directed vertical wind by 9–10 cm/s, whereas a tilt of the layer in drift direction can be excluded.Key words. Atmospheric composition and structure (cloud physics and chemistry; aerosols and particles) Meteorology and atmospheric dynamics (middle atmosphere dynamics)

scholarly journals Total ozone decrease in the Arctic after REP events

2000 ◽  
Vol 18 (3) ◽  
pp. 332-336 ◽  
Author(s):  
V. C. Roldugin ◽  
M. I. Beloglazov ◽  
G. F. Remenets
Keyword(s):  
Total Ozone ◽  
Middle Atmosphere ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Composition And Structure ◽  
Longitudinal Sector ◽  
The Mean ◽  
Polar Meteorology ◽  
The Difference ◽  
Daily Total

Abstract. Eight periods of relativistic electron precipitation (REP) with electron energies of more than 300 keV are identified from VLF data (10-14 kHz) monitored along the Aldra (Norway) - Apatity (Kola peninsula) radio trace. In these cases, anomalous ionization below 55-50 km occurred without disturbing the higher layers of the ionosphere. The daily total ozone values in Murmansk for six days before and six days after the REP events are compared. In seven of eight events a decrease in the total ozone of about 20 DU is observed. In one event of 25 March, 1986, the mean total ozone value for six days before the REP is bigger than that for six days after, but this a case of an extremely high ozone increase (144 DU during the six days). However, on days 3 and 4 there was a minimum of about 47 DU with regard to REP days, so this case also confirms the concept of the ozone decrease after REP. The difference between mean ozone values for periods six days before and six days after the REPs was found also for 23 points in Arctic on TOMS data. The difference was negative only in Murmansk longitudinal sector. Along the meridian of the trace it was negative at high latitudes in both hemispheres and was near zero at low latitudes.Key words: Atmospheric composition and structure (middle atmosphere - composition and chemistry) - Meteorology and atmospheric dynamics (polar meteorology)

scholarly journals Atmospheric composition and structure of HD209458b

2008 ◽  
Vol 4 (S253) ◽  
pp. 524-527
Author(s):  
J.-M. Désert ◽  
A. Vidal-Madjar ◽  
A. Lecavelier des Etangs ◽  
D. Sing ◽  
D. Ehrenreich ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Broad Band ◽  
Temperature Inversion ◽  
Upper Atmosphere ◽  
Atmospheric Composition ◽  
Transmission Spectra ◽  
Transiting Planets ◽  
Atmospheric Composition And Structure ◽  
Composition And Structure ◽  
Sodium Abundance

AbstractTransiting planets like HD209458b offer a unique opportunity to scrutinize their atmospheric composition and structure. Transit spectroscopy probes the transition region between the day and night sides, called the limb. We present a re-analysis of existing HST/STIS transmission spectra of HD209458b's atmosphere. From these observations we identify H2 Rayleigh scattering, derive the absolute Sodium abundance and quantify its depletion in the upper atmosphere, extract a stratospheric T-P profile and find a temperature inversion and explain broad band absorptions with the presence of TiO and VO molecules.

scholarly journals <i>Letter to the Editor</i>Two early observations of aurora at low latitudes

2001 ◽  
Vol 19 (7) ◽  
pp. 809-811 ◽  
Author(s):  
J. M. Vaquero ◽  
M. C. Gallego
Keyword(s):  
Iberian Peninsula ◽  
Atmospheric Dynamics ◽  
Atmospheric Composition ◽  
Magnetospheric Physics ◽  
Present Evidence ◽  
Meteorology And Atmospheric Dynamics ◽  
The North ◽  
Composition And Structure ◽  
Low Latitudes ◽  
Auroral Phenomena

Abstract. It is the purpose of this paper to present evidence concerning the observation of aurorae in the years 880 AD and 942 AD recorded by Arabs from the Iberian Peninsula and the north of Africa.Key words. Meteorology and atmospheric dynamics (general or miscellaneous) – Atmospheric composition and structure (airglow and aurora) – Magnetospheric physics (auroral phenomena)

scholarly journals Extrapolating EISCAT Pedersen conductances to other parts of the sky using ground-based TV auroral images

1998 ◽  
Vol 16 (5) ◽  
pp. 583-588 ◽  
Author(s):  
M. J. Kosch ◽  
T. Hagfors ◽  
K. Schlegel
Keyword(s):  
Individual Case ◽  
Atmospheric Composition ◽  
Large Field ◽  
Hall Conductance ◽  
Ionospheric Conductivity ◽  
Incoherent Scatter ◽  
Composition And Structure ◽  
Incoherent Scatter Radars ◽  
Instruments And Techniques ◽  
Auroral Phenomena

Abstract. Ionospheric conductivity is not very easily measured directly. Incoherent scatter radars perhaps offer the best method but can only measure at one point in the sky at any one time and are limited in their time resolution. Statistical models of average conductivity are available but these may not be applied to individual case studies such as substorms. There are many instances where a real-time estimate of ionospheric conductivity over a large field-of-view is highly desirable at a high temporal and spatial resolution. We show that it is possible to make a reasonable estimate of the noctural height-integrated Pedersen conductivity, or conductance, with a single all-sky TV camera operating at 557.7 nm. This is not so in the case of the Hall conductance where at least two auroral wavelengths should be imaged in order to estimate additionally the energy of the precipitating particles.Key words. Atmospheric composition and structure (airglow and aurora) · Magnetospheric physics (auroral phenomena · instruments and techniques)

scholarly journals On the size distribution of ice-supersaturated regions in the upper troposphere and lowermost stratosphere

2000 ◽  
Vol 18 (4) ◽  
pp. 499-504 ◽  
Author(s):  
K. Gierens ◽  
P. Spichtinger
Keyword(s):  
Size Distribution ◽  
Path Length ◽  
Length Distribution ◽  
Atmospheric Composition ◽  
Trial And Error ◽  
Upper Troposphere ◽  
Composition And Structure ◽  
The Mean ◽  
Path Lengths ◽  
Set Up

Abstract. In order to determine typical sizes of ice-supersaturated regions (ISSRs) in the upper troposphere and lowermost stratosphere we set up the frequency distribution of path lengths flown by MOZAIC aircraft within ISSRs. The mean path length is about 150 km with a standard deviation of 250 km. We analyse the influence of a selection bias (viz. that large ISSRs are more often crossed by aircraft than small ones) on the obtained path length statistics and derive a mathematical equation that relates the path length distribution to the underlying size distribution of ISSRs, assuming that they have circular shape. We solve the equation (by trial and error) and test the result using numerical simulations. Surprisingly, we find that there may be many more very small ISSRs than apparent from the data such that the true mean diameter of the ISSRs may be of the order a few kilometres only. The relevance of the result is discussed and dedicated research flights to measure the true extension of ISSRs are recommended.Key words: Atmospheric composition and structure (troposphere · composition and chemistry; general)

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