Tomoko Kojima

Aerosol particles from tropical convective systems: Cloud tops and cirrus anvils

[1] Aerosol particles from the upper troposphere (UT) and lower stratosphere (LS) were collected during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) and studied by transmission electron microscopy (TEM). Samples were classified into three categories: (1) UT in-cloud, (2) UT out-of-cloud, and (3) LS. Sulfate particles, including former H 2 SO 4 droplets, are dominant in samples from all categories. The morphology of H 2 SO 4 droplets indicates that they had been ammoniated to some extent at the time of collection. They are internally mixed with organic materials, metal sulfates, and solid particles of various compositions. K- and S-bearing organic particles and Si-Al-rich particles are common to the three kinds of samples. In-cloud samples contain abundant Zn-rich particles. Their origin is unclear, but it seems likely that they are contaminants that originated through impact by ice cloud particles on the aircraft or sampling system. Ammoniation and internal mixing of H 2 SO 4 in the UT aerosols may result in freezing at higher temperature than in pure H 2 SO 4 aerosols. The relatively high extent of ammoniation in the UT in-cloud samples may have resulted from vertical transport of ammonia by strong convection. Abundances of nonsulfate particles decrease with increasing altitudes. The nonsulfate particles originated from the lower troposphere and were transported to the UT and LS.

Particle Generation and Resuspension in Aircraft Inlets when Flying in Clouds

Using on-line analysis of single particles, we have observed both generation and resuspension of particles when ice crystals, cloud droplets, or dust impact an aircraft inlet. Large numbers of particles smaller than 1 μ m with a composition suggesting stainless steel were measured when flying a stainless steel inlet through cirrus clouds. Smaller numbers of metal particles were also observed when flying through dust or water clouds. A different instrument, sampling through a different inlet, found zinc particles when sampling in cirrus clouds. Laboratory experiments have verified that high-speed ice crystals can abrade stainless steel. Collision of ice crystals with the inlet wall also resuspended previously deposited particles. A notable example came when a flight through the space shuttle exhaust plume deposited large numbers of unique particles in our inlet. Some of the same types of particles were observed when the aircraft flew into an ice cloud the following day. The generation of particles by impaction of ice crystals and dust in inlets may have affected some published results about ice nuclei and metal particles in the upper troposphere. The newly generated particles cannot be distinguished from atmospheric particles by size alone.

Aerosol particles from tropical convective systems: 2. Cloud bases

Aerosol particles were collected at the altitudes of cloud bases during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) and analyzed using transmission electron microscopy. The particles consist of ammonium sulfate (45-90% by number), sea salt (5-45%), mineral dust (1-20%), and anthropogenic materials such as soot and fly ash (<3%). Ammonium sulfate particles have rather uniform, submicron sizes (mostly 0.5 μm across). Sea-salt particles are larger, apparently having been deliquesced. However, submicron particles are also common. Many contain Na and mixed cation sulfates in addition to NaCl. Mineral dust consists largely of tabular clay particles. Samples from the 28 July flight contain much mineral dust, probably because of transport from the Saharan Desert. Aggregates of sea salt and mineral dust, ammonium sulfate, and soot particles are common. Such mixed aggregates are especially abundant in in-cloud samples. Cirrus samples from CRYSTAL-FACE contain many H 2 SO 4 droplets (Kojima et al., 2004), but acidic sulfate particles are rare at the altitudes of cloud bases. H 2 SO 4 probably formed at higher altitudes through oxidation of SO 2 in cloud droplets. Sea salt and mineral dust have been reported to be abundant in cloud particles collected using a counterflow virtual impactor (Cziczo et al., 2004), suggesting that these particles were incorporated into the convective systems from the cloud bases and akted as ice nuclei while being vertically transported.

Accretion, dispersal, and reaccumulation of the Bishunpur (LL3.1) brecciated chondrite Evidence from troilite-silicate-metal inclusions and chondrule rims

Abstract A set of troilite–silicate–metal (TSM) inclusions and chondrule rims in the Bishunpur (LL3.1) chondrite provide information regarding impact brecciation of small bodies in the early solar system. The TSM inclusions and chondrule rims consist of numerous angular to subrounded silicate grains that are individually enclosed by fine networks of troilite. FeNi metal also occurs in the troilite matrix. The silicates include olivine (Fo55–98), low-Ca pyroxene (En78–98), and high-Ca pyroxene (En48–68Wo11–32). Al- and Si-rich glass coexists with the silicates. Relatively coarse silicate grains are apparently fragments of chondrules typical of petrologic type-3 chondrites. Troilite fills all available cracks and pores in the silicate grains. Some of the TSM inclusions and rims are themselves surrounded by fine-grained silicate-rich rims (FGR). The TSM inclusions and rims texturally resemble the troilite-rich regions in the Smyer H-chondrite breccia. They probably formed by shock-induced mobilization of troilite during an impact event on a primitive asteroidal body. Because silicates in the TSM inclusions and rims have highly unequilibrated compositions, their precursor was presumably type-3 chondritic material like Bishunpur itself. The TSM inclusions and the chondrules with the TSM rims were fragmented and dispersed after the impact-induced compaction, then reaccreted onto the Bishunpur parent body. FGR probably formed around the TSM inclusions and rims, as well as around some chondrules, during the reaccumulation process. Components of most type-2 and 3 chondrites probably experienced similar processing, i.e., dispersal of unconsolidated materials and subsequent reaccumulation.

Asian dust exposure triggers acute myocardial infarction

Aims To elucidate whether Asian dust is associated with the incidence of acute myocardial infarction (AMI) and to clarify whether patients who are highly sensitive to Asian dust will develop AMI. Methods and results Twenty-one participating institutions located throughout Kumamoto Prefecture and capable of performing coronary intervention were included in the study. Data for ground-level observations of Asian dust events were measured at the Kumamoto Local Meteorological Observatory. Data collected between 1 April 2010 and 31 March 2015 were analysed, and 3713 consecutive AMI patients were included. A time-stratified case-crossover design was applied to examine the association between Asian dust exposure and AMI. The occurrence of Asian dust events at 1 day before the onset of AMI was associated with the incidence of AMI [odds ratio (OR), 1.46; 95% confidence interval (CI), 1.09-1.95] and especially, non-ST-segment elevation myocardial infarction was significant (OR 2.03; 95% CI, 1.30-3.15). A significant association between AMI and Asian dust was observed in patients with age ≥75 years, male sex, hypertension, diabetes mellitus, never-smoking status, and chronic kidney disease (CKD). However, Asian dust events had a great impact on AMI onset in patients with CKD (P < 0.01). A scoring system accounting for several AMI risk factors was developed. The occurrence of Asian dust events was found to be significantly associated with AMI incidence among patients with a risk score of 5-6 (OR 2.45; 95% CI: 1.14-5.27). Conclusion Asian dust events may lead to AMI and have a great impact on its onset in patients with CKD.

The Geology of Japan

It has been 25 years since publication of the most recent English language summary of the geology of Japan. This book offers an up-to-date comprehensive guide for those interested both in the geology of the Japanese islands and geological processes of island arcs in general. It contains contributions from over 70 different eminent researchers in their fields and is divided into 12 main chapters: Each chapter includes the unique contribution of an extensive aid to the written forms of geology-related names in Japanese.