24 research outputs found

    Validation of ozone data from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

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    The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) onboard the International Space Station provided global measurements of ozone profiles in the middle atmosphere from 12 October 2009 to 21 April 2010. We present validation studies of the SMILES version 2.1 ozone product based on coincidence statistics with satellite observations and outputs of chemistry and transport models (CTMs). Comparisons of the stratospheric ozone with correlative data show agreements that are generally within 10%. In the mesosphere, the agreement is also good and better than 30% even at a high altitude of 73km, and the SMILES measurements with their local time coverage also capture the diurnal variability very well. The recommended altitude range for scientific use is from 16 to 73km. We note that the SMILES ozone values for altitude above 26km are smaller than some of the correlative satellite datasets; conversely the SMILES values in the lower stratosphere tend to be larger than correlative data, particularly in the tropics, with less than 8% difference below similar to 24km. The larger values in the lower stratosphere are probably due to departure of retrieval results between two detection bands at altitudes below 28km; it is similar to 3% at 24km and is increasing rapidly down below

    The Arrival Direction Distribution of Extremely High Energy Cosmic Rays Observed by AGASA

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    Study of the arrival direction distribution plays a key role in finding sources of the Extremely High Energy Cosmic Rays (EHECR). Greisen-Zatsepin-Kuz\u27min (GZK) mechanism limits the propagation of EHE cosmic rays significantly and only nearby sources can contribute to the local EHECR flux. Furthermore EHECRs travel intergalactic spaces almost linearly. Hence, we expect they can be traced back to their sources. Here we report a small-sacle anisotropy of the arrival direction distribution of EHECRs observed by AGASA above 1019eV . This result strongly suggests the existence of point sources of EHECRs

    Chemical Composition of Ultra-High Energy Cosmic Rays Observed by AGASA

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    We have observed ultra-high energy cosmic rays above the Greisen-Zatsepin-Kuz\u27min cut-off energy by Akeno Giant Air Shower Array. Their chemical composition is a key discriminator of origin models. In the present work, we estimate the average composition by an analysis of muons in air showers with AIRES+QGSJET simulation. The data matches the prediction for light hadron primaries and no indication has been found for a gamma-ray dominance
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