JpGU-AGU Joint Meeting 2020

Presentation information

[J] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG58] Aircraft and UAV Observations for Earth-planetary sciences

convener:Nobuhiro Takahashi(Institute for Space-Earth Environmental Research, Nagoya University), Makoto Koike(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Toshinobu Machida(National Institute for Environmental Studies), Taro Shinoda(Institute for Space-Earth Environmental Research, Nagoya University)

[ACG58-05] Abundances of black carbon and iron oxide aerosols over East Asia and the Arctic from the aircraft measurements

*Atsushi Yoshida1, Nobuhiro Moteki1, Sho Ohata2, Tatsuhiro Mori3, Makoto Koike1, Yutaka Kondo4, Hitoshi MATSUI5, Naga Oshima6, Akinori Takami7, Kazuyuki Kita8 (1.Graduate School of Science, The University of Tokyo, 2.Institute for Space–Earth Environmental Research, Nagoya University, 3.Faculty of Science, Tokyo University of Science, 4.National Institute of Polar Research, 5.Graduate School of Environmental Studies, Nagoya University, 6.Meteorological Research Institute, 7.National Institute of Environmental Studies, 8.Faculty of Science, Ibaraki University)

Keywords:aircraft measurement, black carbon, iron, East Asia, Arctic

Black carbon (BC) and light-absorbing iron oxides (FeOx) aerosols affect Earth’s energy budget through their strong absorption of solar radiation. FeOx aerosols can also affect global biogeochemical cycles through their role as a nutrient for oceanic phytoplankton. However, observational data (atmospheric concentrations and microphysical properties) for these light-absorbing aerosols, required for evaluating their effects using global climate models, are scarce, especially for FeOx. Here, we summarize and compare the datasets of BC and FeOx from three aircraft observation campaigns: A-FORCE 2009 and 2013W (Aerosol Radiative Forcing in East Asia) and PAMARCMiP 2018 (Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project), all of which relied on the same instrument, a modified single-particle soot photometer.

In these campaigns, > 80% of FeOx-containing aerosols in the 170–270 nm size range had microphysical features indicating an anthropogenic origin. The mass concentrations of FeOx were ~100–400 ng/m3 in East Asia (A-FORCE 2009 and 2013W) but as low as ~5 ng/m3 in the Arctic (PAMARCMiP 2018); the corresponding values for BC were ~300–1000 ng/m3 in East Asia and ~25 ng/m3 in the Arctic. Despite these large variabilities in mass concentration, the mass ratios of FeOx/BC had a narrow range within ~0.2–0.5. In all observations, FeOx, BC, and carbon monoxide (CO) concentrations were strongly correlated with each other. These results indicate that FeOx, BC, and CO were emitted in nearly the same areas with similar emission ratios.

In the two East Asian campaigns (A-FORCE 2009 and 2013W), BC mass concentrations tended to decrease with altitude, but there was no such tendency in the Arctic campaign (PAMARCMiP 2018); the peak in BC concentration in PAMARCMiP 2018 locates at the highest altitude (~5 km), which might be contributed from emissions in lower-latitude sources.

The FeOx/BC mass concentration ratios tended to increase with altitude in the A-FORCE 2009 and 2013W datasets from East Asia. This result might be due to an increased contribution of FeOx-containing mineral dust at higher altitudes. In contrast, this ratio tended to decrease with increasing altitude in the Arctic dataset (PAMARCMiP 2018). The altitude dependence of the particle-size distribution of FeOx in the PAMARCMiP 2018 dataset shows that, in contrast to the A-FORCE 2009 and 2013W campaign, large FeOx particles (>1 µm) were not observed in high altitudes. These contrasts between the East Asian and Arctic regions might reflect differences in the fractional contribution of windblown mineral dust particles from desert regions and in the effect of wet removal processes during the transport of FeOx from its source regions.

Abundances of BC and FeOx using the dataset obtained from ground measurements in addition to aircraft measurements will also be discussed in the presentation.