• Title/Summary/Keyword: global mass extinction

Search Result 5, Processing Time 0.023 seconds

Estimation of Particle Mass Concentration from Lidar Measurement (라이다 관측자료를 이용한 미세먼지 농도 산정)

  • Kim, Man-Hae;Yeo, Huidong;Sugimoto, Nobuo;Lim, Han-Cheol;Lee, Chul-Kyu;Heo, Bok-Haeng;Yu, Yung-Suk;Sohn, Byung-Ju;Yoon, Soon-Chang;Kim, Sang-Woo
    • Atmosphere
    • /
    • v.25 no.1
    • /
    • pp.169-177
    • /
    • 2015
  • Vertical distribution of particle mass concentrations was estimated from 8-year elastic-backscatter lidar and sky radiometer data, and from ground-level PM10 concentrations measured in Seoul. Lidar ratio and mass extinction efficiency were determined from aerosol optical depth (AOD) and ground-level PM10 concentrations, which were used as constraints to estimate particle mass concentration. The mean lidar ratio (with standard deviation) and mass extinction efficiency for the entire 8-year study period were $60.44{\pm}23.17$ sr and $3.69{\pm}3.00m^2g^{-1}$, respectively. The lidar ratio did not vary significantly with the ${\AA}ngstr{\ddot{o}}m$ exponent (less than ${\pm}10%$); however, the mass extinction efficiency decreases to $1.82{\pm}1.67m^2g^{-1}$ (51% less than the mean value) when the ${\AA}ngstr{\ddot{o}}m$ exponent is less than 0.5. This result implies that the particle mass concentration from lidar measurements can be underestimated for dust events. Seasonal variation of the particle mass concentration estimated from lidar measurements for the boundary layer, was quite different from ground-level PM10 measurements. This can be attributable to an inhomogeneous vertical distribution of aerosol in the boundary layer.

Global Science Literacy

  • Mayer, Victor J.
    • 한국지구과학회:학술대회논문집
    • /
    • 2003.09a
    • /
    • pp.15-17
    • /
    • 2003
  • Global Science Literacy is proposed as an international curriculum standard for science literacy. It is based on the science curriculum construct of Earth Systems Education, which has come out of the earth science education community in the United States. The presentation will briefly describe the nature of ESE, and include, if sufficient time, an audience participation simulation of mass extinction.

  • PDF

The Dependence of Type Ia Supernova Luminosities on the Global and Local Properties of Host Galaxies in the YONSEI Supernova Catalog

  • Kim, Young-Lo;Kang, Yijung;Lee, Young-Wook
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.43 no.1
    • /
    • pp.62.3-63
    • /
    • 2018
  • Trends of Type Ia supernova (SN Ia) luminosities with the properties of host galaxies are important to study the underlying physics for an SN progenitor system and explosion mechanism. In the YONSEI SN catalog, we have a sample of ~600 SN and host data in the wider redshift range, and two independent light-curve models, SALT2 and MLCS2k2. From this catalog, here we present that SNe Ia in low-mass, globally and locally star-forming environments are fainter than those in high-mass, globally and locally passive environments, after light-curve shape and color or extinction corrections. Our results are then compared to previous studies, and show consistent results.

  • PDF

A SYSTEMATIC STUDY OF DUST IN EARLY-TYPE GALAXIES WITH AKARI

  • Kokusho, Takuma;Kaneda, Hidehiro;Kondo, Toru;Oyabu, Shinki;Yamagishi, Mitsuyoshi;Murata, Katsuhiro
    • Publications of The Korean Astronomical Society
    • /
    • v.32 no.1
    • /
    • pp.151-153
    • /
    • 2017
  • Early-type galaxies (ETGs) are generally dominated by old low-mass stars, which are not very productive of dust, and hot interstellar plasmas, which are very destructive of dust. Thus ETGs provide harsh environments for survival of dust. It has been found that some ETGs contain a large amount of dust, and yet its supply mechanism is not understood well. We present the result of a systematic study of dust in ETGs with the AKARI mid- and far-infrared all-sky surveys. From the AKARI result and the Ks band data obtained by ground-based telescopes, we find that there is a global correlation between the dust mass and stellar luminosity. We also compare the AKARI all-sky survey result with the CO data to discuss origins of dust in ETGs.

THERRESTRIAL IMPACT CRATERING CHRONOLOGY: A PRELIMINARY ANALYSIS

  • Moon, Hong-Kyu;Mi, Byung-Hee;Fletcher, Andre-B.;Kim, Bong-Gyu
    • Journal of Astronomy and Space Sciences
    • /
    • v.18 no.3
    • /
    • pp.191-208
    • /
    • 2001
  • We have recently compiled a database of the properties of 192 impact craters, which supercedes previous compilations. Using our database, the impact structures found in North America, Europe and Australia have been examined; these cratonic areas have been relatively stable for considerably long geological periods, and thus have been best preserved. It is confirmed that there is a close correlation between the geological epoch boundaries, the epochs of mass extinctions, antral the "timing" of impacts. In addition, the terrestrial cumulative flux of objects >20km is found to be $1.77{\times}10^{-15}km^{-2}yr^{-1}$, over the last 120 Myr, which is much smaller than the published values in McEwen et al. (1997) and Shoemaker (1998) ($5.6{\pm}2.8{\times}10^{-15}km^{-2}yr^{-1}$. For terrestrial impact structures with D> 50 km, the apparent cumulative flux over the last 2450 Myr is ~50 times smaller than the corresponding value for the Moon. If we assume that the Earth and the Moon suffered the same level of bombardment over this time, this would mean that the actual flux of impacting bodies, capable of making craters with D)50 km, was ~ 50 times larger than the apparent flux estimated from the currently known terrestrial records.

  • PDF