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  • Copernicus GmbH  (4)
  • 1
    In: Annales Geophysicae, Copernicus GmbH, Vol. 19, No. 10/12 ( 2001-09-30), p. 1303-1354
    Abstract: Abstract. On board the four Cluster spacecraft, the Cluster Ion Spectrometry (CIS) experiment measures the full, three-dimensional ion distribution of the major magnetospheric ions (H+, He+, He++, and O+) from the thermal energies to about 40 keV/e. The experiment consists of two different instruments: a COmposition and DIstribution Function analyser (CIS1/CODIF), giving the mass per charge composition with medium (22.5°) angular resolution, and a Hot Ion Analyser (CIS2/HIA), which does not offer mass resolution but has a better angular resolution (5.6°) that is adequate for ion beam and solar wind measurements. Each analyser has two different sensitivities in order to increase the dynamic range. First tests of the instruments (commissioning activities) were achieved from early September 2000 to mid January 2001, and the operation phase began on 1 February 2001. In this paper, first results of the CIS instruments are presented showing the high level performances and capabilities of the instruments. Good examples of data were obtained in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind and cusp measurements. Observations in the auroral regions could also be obtained with the Cluster spacecraft at radial distances of 4–6 Earth radii. These results show the tremendous interest of multispacecraft measurements with identical instruments and open a new area in magnetospheric and solar wind-magnetosphere interaction physics.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetopheric configuration and dynamics; solar wind - magnetosphere interactions)
    Type of Medium: Online Resource
    ISSN: 1432-0576
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2001
    detail.hit.zdb_id: 1458425-6
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  • 2
    Online Resource
    Online Resource
    Copernicus GmbH ; 2010
    In:  Atmospheric Chemistry and Physics Vol. 10, No. 3 ( 2010-02-01), p. 895-907
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 10, No. 3 ( 2010-02-01), p. 895-907
    Abstract: Abstract. This paper reports the first record of extreme ozone measurements in Africa. As part of the AMMA program, the ozone vertical profile recorded on 20 December over Cotonou presents exceptionally high ozone concentrations with up to 295 ppb at 1 km altitude. Retroplumes from the Flexpart model show that the air masses sampled at 1 km over Cotonou on this day came from the burning area situated north-east of Cotonou and passed over Lagos, Nigeria, which is highly impacted by urban pollution. We used the Master Mechanism box model to simulate the chemical composition of the plume during its transit. We find that neither the biomass burning emissions of ozone precursors nor additional urban emissions from Lagos are high enough to simulate more than 120–150 ppb of ozone. The only way to reach almost 300 ppb of ozone within a few hours is to feed the air mass with large amounts of reactive VOCs as those recorded in the vicinity of petrochemical area. Sensitivity tests show that 250–600 ppb of VOCs combined with 35–80 ppb of NOx allow the ozone concentrations to be higher than 250 ppb. Nigeria is the first African country with gas extraction and petrochemical industries, and petrochemical explosions frequently happen in the vicinity of Lagos. The hypothesis of a petrochemical explosion in this area is the most likely scenario which could explain the 295 ppb ozone maximum measured over Cotonou, downwind of Lagos.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2010
    detail.hit.zdb_id: 2092549-9
    detail.hit.zdb_id: 2069847-1
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  • 3
    Online Resource
    Online Resource
    Copernicus GmbH ; 2014
    In:  Geoscientific Model Development Vol. 7, No. 4 ( 2014-08-14), p. 1661-1669
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 7, No. 4 ( 2014-08-14), p. 1661-1669
    Abstract: Abstract. In the case of infinite plane-parallel single- and double-layered cloud, the solar irradiance at ground level computed by a radiative transfer model can be approximated by the product of the irradiance under clear atmosphere and a modification factor due to cloud properties and ground albedo only. Changes in clear-atmosphere properties have negligible effect on the latter so that both terms can be calculated independently. The error made in using this approximation depends mostly on the solar zenith angle, the ground albedo and the cloud optical depth. In most cases, the maximum errors (95th percentile) on global and direct surface irradiances are less than 15 W m−2 and less than 2–5% in relative value. These values are similar to those recommended by the World Meteorological Organization for high-quality measurements of the solar irradiance. Practically, the results mean that a model for fast calculation of surface solar irradiance may be separated into two distinct and independent models, possibly abacus-based, whose input parameters and resolutions can be different, and whose creation requires less computation time and resources than a single model.
    Type of Medium: Online Resource
    ISSN: 1991-9603
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2014
    detail.hit.zdb_id: 2456725-5
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  • 4
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 7, No. 5 ( 2014-10-16), p. 2409-2409
    Type of Medium: Online Resource
    ISSN: 1991-9603
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2014
    detail.hit.zdb_id: 2456725-5
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