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Increase in upper tropospheric and lower stratospheric aerosol levels and its potential connection with Asian pollution

På svenska

Author

  • J. -P. Vernier
  • T. D. Fairlie
  • M. Natarajan
  • F. G. Wienhold
  • J. Bian
  • Bengt Martinsson
  • S. Crumeyrolle
  • L. W. Thomason
  • K. M. Bedka

Summary, in English

Satellite observations have shown that the Asian Summer Monsoon strongly influences the upper troposphere and lower stratosphere (UTLS) aerosol morphology through its role in the formation of the Asian Tropopause Aerosol Layer (ATAL). Stratospheric Aerosol and Gas Experiment II solar occultation and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar observations show that summertime UTLS Aerosol Optical Depth (AOD) between 13 and 18 km over Asia has increased by three times since the late 1990s. Here we present the first in situ balloon measurements of aerosol backscatter in the UTLS from Western China, which confirm high aerosol levels observed by CALIPSO since 2006. Aircraft in situ measurements suggest that aerosols at lower altitudes of the ATAL are largely composed of carbonaceous and sulfate materials (carbon/sulfur elemental ratio ranging from 2 to 10). Back trajectory analysis from Cloud-Aerosol Lidar with Orthogonal Polarization observations indicates that deep convection over the Indian subcontinent supplies the ATAL through the transport of pollution into the UTLS. Time series of deep convection occurrence, carbon monoxide, aerosol, temperature, and relative humidity suggest that secondary aerosol formation and growth in a cold, moist convective environment could play an important role in the formation of ATAL. Finally, radiative calculations show that the ATAL layer has exerted a short-term regional forcing at the top of the atmosphere of -0.1 W/m(2) in the past 18 years.

Publishing year

2015

Language

English

Pages

1608-1619

Publication/Series

Journal of Geophysical Research: Atmospheres

Volume

120

Issue

4

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Production Engineering, Human Work Science and Ergonomics

Status

Published

ISBN/ISSN/Other

  • ISSN: 2169-8996