scholarly journals Late spring ultraviolet levels over the United Kingdom and the link to ozone

1999 ◽  
Vol 17 (9) ◽  
pp. 1199-1209 ◽  
Author(s):  
J. Austin ◽  
C. M. H. Driscoll ◽  
S. F. G. Farmer ◽  
M. J. Molyneux
Keyword(s):  
Total Ozone ◽  
Middle Atmosphere ◽  
Atmospheric Dynamics ◽  
Atmospheric Composition ◽  
Radiative Processes ◽  
The United Kingdom ◽  
Chemical Effects ◽  
Composition And Structure ◽  
Time Of Year ◽  
First Time

Abstract. Erythemally-weighted ultraviolet (UVery) levels measured over southern England, during anticyclonic weather between 30 April and 2 May, 1997, were almost 50 higher than normally expected for clear skies and were similar to mid-summer values for the first time since measurements began in 1990. Investigation of this episode suggests that a combination of both meteorological and chemical effects were responsible for generating record low ozone amounts for the time of year. Further, comparisons between the A band ultraviolet (315 to 400 nm wavelength) amounts, and radiative calculations confirm that the high UVery was primarily due to the reduction in total ozone. These results are contrasted with a similar period for 1998, in which near climatological ozone amounts were measured. The prospects for enhanced UVery levels in future years are briefly reviewed in the light of expected increases in stratospheric halogen levels and greenhouse gases.Key words. Atmospheric composition and structure (middle atmosphere · composition and chemistry) · Meterology and atmospheric dynamics (middle atmosphere dynamics; radiative processes)

scholarly journals Validation of GOME total ozone by means of the Norwegian ozone monitoring network

1999 ◽  
Vol 17 (3) ◽  
pp. 430-436 ◽  
Author(s):  
G. Hansen ◽  
A. Dahlback ◽  
F. Tønnessen ◽  
T. Svenøe
Keyword(s):  
Total Ozone ◽  
Middle Atmosphere ◽  
Monitoring Network ◽  
High Arctic ◽  
Atmospheric Composition ◽  
Pixel Size ◽  
Composition And Structure ◽  
Instruments And Techniques ◽  
Ozone Monitoring ◽  
Good Agreement

Abstract. The Global Ozone Monitoring Experiment (GOME) onboard the ERS-2 satellite has been in operation since July 1995. The Norwegian ground-based total ozone network has played an important role both in the main validation during the commissioning phase and in the validation of upgraded versions of the analysis algorithms of the instrument. The ground-based network consists of various spectrometer types (Dobson, Brewer, UV filter instruments). The validation of the second algorithm version used until January 1998 reveals a very good agreement between GOME and ground-based data at solar zenith angles <60° and deviations of GOME total ozone data from ground-based data of up to ±60 DU (~20%) at zenith angles >60°. The deviations strongly depend on the season of the year, being negative in summer and positive in winter/spring, The deviations furthermore show a considerable scattering (up to ±25 DU in monthly average values of 5° SZA intervals), even in close spatial and temporal coincidence with ground-based measurements, especially in the high Arctic. The deviations are also dependent on the viewing geometry/ground pixel size with an additional negative offset for the large pixels used in the backswath mode and at solar zenith angles >85°, compared to forward-swath pixels.Key words. Atmospheric composition and structure (middle atmosphere · composition and chemistry; instruments and techniques)

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 Rarefied gas flows through meshes and implications for atmospheric measurements

2001 ◽  
Vol 19 (5) ◽  
pp. 563-569 ◽  
Author(s):  
J. Gumbel
Keyword(s):  
Middle Atmosphere ◽  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Atmospheric Composition ◽  
Gas Flows ◽  
Atmospheric Measurements ◽  
Rarefied Gas Flows ◽  
Flow Disturbances ◽  
Composition And Structure ◽  
Compression Effects

Abstract. Meshes are commonly used as part of instruments for in situ atmospheric measurements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Simulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes freely exposed to the flow, substantial compression effects are found both upstream and downstream of the mesh. Meshes attached to close instrument structures, on the other hand, cause only minor flow disturbances. In an accompanying paper, the approach developed here is applied to the quantitative analysis of rocket-borne density measurements in the middle atmosphere.Key words. Atmospheric composition and structure (instruments and techniques; middle atmosphere – composition and chemistry)

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 front observations by the OH airglow imager carried out at Ferraz Station on King George Island, Antarctic Peninsula, in 2011

2018 ◽  
Vol 36 (1) ◽  
pp. 253-264 ◽  
Author(s):  
Gabriel Augusto Giongo ◽  
José Valentin Bageston ◽  
Paulo Prado Batista ◽  
Cristiano Max Wrasse ◽  
Gabriela Dornelles Bittencourt ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Near Infrared ◽  
Middle Atmosphere ◽  
Convective Cloud ◽  
Atmospheric Composition ◽  
Secondary Wave ◽  
King George Island ◽  
Composition And Structure ◽  
Waves And Tides ◽  
Energy And Momentum

Abstract. The main goals of this work are to characterize and investigate the potential wave sources of four mesospheric fronts identified in the hydroxyl near-infrared (OH-NIR) airglow images, obtained with an all-sky airglow imager installed at Comandante Ferraz Antarctic Station (EACF, as per its Portuguese acronym) located on King George Island in the Antarctic Peninsula. We identified and analyzed four mesospheric fronts in 2011 over King George Island. In addition, we investigate the atmospheric background environment between 80 and 100 km altitude and discuss the ducts and propagation conditions for these waves. For that, we used wind data obtained from a meteor radar operated at EACF and temperature data obtained from the TIMED/SABER satellite. The vertical wavenumber squared, m2, was calculated for each of the four waves. Even though no clearly defined duct (indicated by positive values of m2 sandwiched between layers above and below with m2  < 0) was found in any of the events, favorable propagation conditions for horizontal propagation of the fronts were found in three cases. In the fourth case, the wave front did not find any duct support and it appeared to dissipate near the zenith, transferring energy and momentum to the medium and, consequently, accelerating the wind in the wave propagation direction (near to south) above the OH peak (88–92 km). The likely wave sources for these four cases were investigated by using meteorological satellite images and in two cases we could find that strong instabilities were potential sources, i.e., a cyclonic activity and a large convective cloud cell. In the other two cases it was not possible to associate troposphere sources as potential candidates for the generation of such wave fronts observed in the mesosphere and secondary wave sources were attributed to these cases. Keywords. Atmospheric composition and structure (airglow and aurora) – meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

scholarly journals Surface ultraviolet radiation over east Siberia: seasonal variations

2002 ◽  
Vol 20 (4) ◽  
pp. 559-564
Author(s):  
A. V. Mikhalev ◽  
M. A. Chernigovskaya ◽  
A. Yu. Shalin ◽  
E. S. Kazimirovsky
Keyword(s):  
Ultraviolet Radiation ◽  
Uv Radiation ◽  
Middle Atmosphere ◽  
Ground Level ◽  
Atmospheric Composition ◽  
Time Interval ◽  
East Siberia ◽  
Solar Ultraviolet Radiation ◽  
Composition And Structure ◽  
Asymmetric Behaviour

Abstract. The results of spectral measurements of the daily near-noon surface direct solar ultraviolet radiation in the wavelength range of 295–345 nm obtained in Irkutsk (East Siberia) for the time interval of 1998–2000 are presented. For the period under consideration, the seasonal UV radiation variations are analysed that are associated with the total ozone dynamics, the transition of cyclonic and anticyclonic (Siberian anticyclone) periods, the presence of snow cover, and other factors. The analysis reveals an asymmetric behaviour of the seasonal course in ground-level UV radiation around the time of the summer solstice, with seasonal variation dependence on the wavelength. We have determined the irregular variations of surface UV radiation that is typical for the region, with their properties dependent on the season and on the spectral range analysed. The similarity of the above noted features from year to year was revealed.Key words. Atmospheric composition and structure (Transmission and scattering of radiation; instruments and techniques) – Meteorology and atmospheric dynamics (middle atmosphere dynamics)

scholarly journals Estonian total ozone climatology

2002 ◽  
Vol 20 (2) ◽  
pp. 247-255 ◽  
Author(s):  
K. Eerme ◽  
U. Veismann ◽  
R. Koppel
Keyword(s):  
Total Ozone ◽  
Middle Atmosphere ◽  
Power Spectra ◽  
Ground Level ◽  
Atmospheric Composition ◽  
Trend Detection ◽  
Phase Lag ◽  
Quasi Biennial Oscillation ◽  
Significance Level ◽  
The One

Abstract. The climatological characteristics of total ozone over Estonia based on the Total Ozone Mapping Spectrometer (TOMS) data are discussed. The mean annual cycle during 1979–2000 for the site at 58.3° N and 26.5° E is compiled. The available ground-level data interpolated before TOMS, have been used for trend detection. During the last two decades, the quasi-biennial oscillation (QBO) corrected systematic decrease of total ozone from February–April was 3 ± 2.6% per decade. Before 1980, a spring decrease was not detectable. No decreasing trend was found in either the late autumn ozone minimum or in the summer total ozone. The QBO related signal in the spring total ozone has an amplitude of ± 20 DU and phase lag of 20 months. Between 1987–1992, the lagged covariance between the Singapore wind and the studied total ozone was weak. The spring (April–May) and summer (June–August) total ozone have the best correlation (coefficient 0.7) in the yearly cycle. The correlation between the May and August total ozone is higher than the one between the other summer months. Seasonal power spectra of the total ozone variance show preferred periods with an over 95% significance level. Since 1986, during the winter/spring, the contribution period of 32 days prevails instead of the earlier dominating 26 days. The spectral densities of the periods from 4 days to 2 weeks exhibit high interannual variability.Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry; volcanic effects) – Meteorology and atmospheric dynamics (climatology)

scholarly journals Ultrafast Kelvin waves in the MLT airglow and wind, and their interaction with the atmospheric tides

2018 ◽  
Vol 36 (1) ◽  
pp. 231-241 ◽  
Author(s):  
Fabio Egito ◽  
Ricardo Arlen Buriti ◽  
Amauri Fragoso Medeiros ◽  
Hisao Takahashi
Keyword(s):  
Middle Atmosphere ◽  
Rotational Temperature ◽  
Meridional Wind ◽  
Equatorial Region ◽  
Kelvin Waves ◽  
Atmospheric Composition ◽  
Atmospheric Tides ◽  
Kelvin Wave ◽  
Composition And Structure ◽  
Integrated Intensities

Abstract. Airglow and wind measurements from the Brazilian equatorial region were used to investigate the presence and the effects of the 3–4-day ultrafast Kelvin waves in the MLT. The airglow integrated intensities of the OI557.7 nm, O2b(0-1) and OH(6-2) emissions, as well as the OH rotational temperature, were measured by a multichannel photometer, and the zonal and meridional wind components between 80 and 100 km were obtained from a meteor radar. Both instruments are installed in the Brazilian equatorial region at São João do Cariri (7.4∘ S, 36.5∘ W). Data from 2005 were used in this study. The 3–4-day oscillations appear intermittently throughout the year in the airglow. They were identified in January, March, July, August and October–November observations. The amplitudes induced by the waves in the airglow range from 26 to 40 % in the OI557.7 nm, 17 to 43 % in the O2b(0-1) and 15 to 20 % in the OH(6-2) emissions. In the OH rotational temperature, the amplitudes were from 4 to 6 K. Common 3–4-day oscillations between airglow and neutral wind compatible with ultrafast Kelvin waves were observed in March, August and October–November. In these cases, the amplitudes in the zonal wind were found to be between 22 and 28 m s−1 and the vertical wavelength ranges from 44 to 62 km. Evidence of the nonlinear interaction between the ultrafast Kelvin wave and diurnal tide was observed. Keywords. Atmospheric composition and structure (airglow and aurora) – meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

scholarly journals Statistical interpolation of ozone measurements from satellite data (TOMS, SBUV and SAGE II) using the kriging method

2000 ◽  
Vol 18 (6) ◽  
pp. 666-678 ◽  
Author(s):  
B. J. S. Tranchant ◽  
A. P. Vincent
Keyword(s):  
Satellite Data ◽  
Middle Atmosphere ◽  
Stratospheric Aerosol ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Global Correlation ◽  
Composition And Structure ◽  
Data Resolution ◽  
High Vertical Resolution ◽  
Statistical Interpolation

Abstract. This study demonstrates that ordinary kriging in spherical coordinates using experimental semi-variograms provides highly usable results, especially near the pole in winter and/or where there could be data missing over large areas. In addition, kriging allows display of the spatial variability of daily ozone measurements at different pressure levels. Three satellite data sets were used: Total Ozone Mapping Spectrometer (TOMS) data, Solar Backscattered UltraViolet (SBUV), and the Stratospheric Aerosol and Gas Experiment (SAGE II) ozone profiles. Since SBUV is a nadir-viewing instrument, measurements are only taken along the sun-synchronous polar orbits of the satellite. SAGE II is a limb-viewing solar occultation instrument, and measurements have high vertical resolution but poor daily coverage. TOMS has wider coverage with equidistant distribution of data  (resolution 1° × 1.25°) but provides no vertical information. Comparisons of the resulting SBUV-interpolated (column-integrated) ozone field with TOMS data are strongly in agreement, with a global correlation of close to 98%. Comparisons of SBUV-interpolated ozone profiles with daily SAGE II profiles are relatively good, and comparable to those found in the literature. The interpolated ozone layers at different pressure levels are shown.Key words: Atmospheric composition and structure (middle atmosphere - composition and chemistry) - Meteorology and atmospheric dynamics (middle atmosphere dynamics)

scholarly journals Using routine meteorological data to derive sky conditions

2003 ◽  
Vol 21 (3) ◽  
pp. 649-654 ◽  
Author(s):  
D. Pagès ◽  
J. Calbó ◽  
J. A. González
Keyword(s):  
Solar Radiation ◽  
Meteorological Data ◽  
Atmospheric Composition ◽  
Likelihood Method ◽  
Total Solar Radiation ◽  
The Public ◽  
Radiative Processes ◽  
Composition And Structure ◽  
Real Time Information ◽  
Sky Conditions

Abstract. Sky condition is a matter of interest for public and weather predictors as part of weather analyses. In this study, we apply a method that uses total solar radiation and other meteorological data recorded by an automatic station for deriving an estimation of the sky condition. The impetus of this work is the intention of the Catalan Meteorological Service (SMC) to provide the public with real-time information about the sky condition. The methodology for deriving sky conditions from meteorological records is based on a supervised classification technique called maximum likelihood method. In this technique we first need to define features which are derived from measured variables. Second, we must decide which sky conditions are intended to be distinguished. Some analyses have led us to use four sky conditions: (a) cloudless or almost cloudless sky, (b) scattered clouds, (c) mostly cloudy – high clouds, (d) overcast – low clouds. An additional case, which may be treated separately, corresponds to precipitation (rain or snow). The main features for estimating sky conditions are, as expected, solar radiation and its temporal variability. The accuracy of this method of guessing sky conditions compared with human observations is around 70% when applied to four sites in Catalonia (NE Iberian Peninsula). The agreement increases if we take into account the uncertainty both in the automatic classifier and in visual observations.Key words. Meteorological and atmospheric dynamics (instruments and techniques; radiative processes) – Atmospheric composition and structure (cloud physics and chemistry)

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