The role of humic-like substances as atmospheric surfactants in the formation of summer-heavy rainfall in downtown Tokyo

Toshiki Sugo*, Hiroshi Okochi, Ryunosuke Uchiyama, Eri Yamanokoshi, Hiroko Ogata, Naoya Katsumi, Takanori Nakano

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

In order to study the impact of organic aerosols in the formation of UHR (hereafter UHR = urban-induced heavy rain), we analyzed humic-like substances (hereafter HULIS) that serve as major atmospheric surfactants as well as the major inorganic ions in rainwater collected on an event basis at the Nishi-Waseda Campus of Waseda University in Shinjuku, Tokyo. Fulvic and humic acid fractions in HULIS was determined by the DEAE (Diethylaminoethyl cellulose) -UV method. The total wet deposition flux of HULIS in UHR was 33.5 times higher than that found in a normal rainfall and 57.3 times higher than that found in THR (hereafter THR = typhoon heavy rain). The accumulation of HULIS to acidic anions such as NO3 and SO42− in UHR compared to other types of rain indicates that HULIS in UHR accelerated the growth of cloud droplets via reduction of surface tension, which likely led to the rapid development of cumulonimbus clouds.

Original languageEnglish
Article number100022
JournalCity and Environment Interactions
Volume3
DOIs
Publication statusPublished - 2019 Nov

Keywords

  • Cloud droplet growth
  • Cumulonimbus development
  • Urban heat island
  • Urban-induced heavy rain

ASJC Scopus subject areas

  • Environmental Science (miscellaneous)
  • Management, Monitoring, Policy and Law
  • Geography, Planning and Development
  • Urban Studies

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