FastFind »   Lastname: doi:10.1029/ Year: | Advanced Search  

AGU: Geophysical Research Letters

 

Keywords

  • nitric acid
  • subvisible cirrus
  • tropical tropopause

Index Terms

  • Atmospheric Composition and Structure: Cloud physics and chemistry
  • Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry
  • Atmospheric Composition and Structure: Troposphere: composition and chemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L24812, 5 PP., 2007
doi:10.1029/2007GL031832

Condensed-phase nitric acid in a tropical subvisible cirrus cloud

P. J. Popp

Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA

T. P. Marcy

Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA

L. A. Watts

Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA

R. S. Gao

Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA

D. W. Fahey

Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA

E. M. Weinstock

Atmospheric Research Project, Harvard University, Cambridge, Massachusetts, USA

J. B. Smith

Atmospheric Research Project, Harvard University, Cambridge, Massachusetts, USA

R. L. Herman

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

R. F. Troy

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

C. R. Webster

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

L. E. Christensen

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

D. G. Baumgardner

Centro de Ciencias de la Atmosfera, Universidad Nacional Autónoma de México, Mexico City, Mexico

C. Voigt

Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany

B. Kärcher

Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany

J. C. Wilson

Department of Engineering, University of Denver, Denver, Colorado, USA

M. J. Mahoney

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA

E. J. Jensen

NASA Ames Research Center, Moffett Field, California, USA

T. P. Bui

NASA Ames Research Center, Moffett Field, California, USA

In situ observations in a tropical subvisible cirrus cloud during the Costa Rica Aura Validation Experiment on 2 February 2006 show the presence of condensed-phase nitric acid. The cloud was observed near the tropopause at altitudes of 16.3–17.7 km in an extremely cold (183–191 K) and dry (<5 ppm H2O) air mass. Relative humidities with respect to ice ranged from 150–250% throughout most of the cloud. Optical particle measurements indicate the presence of ice crystals as large as 90 μm in diameter. Condensed HNO3/H2O molar ratios observed in the cloud particles were 1–2 orders of magnitude greater than ratios observed previously in cirrus clouds at similar HNO3 partial pressures. Nitric acid trihydrate saturation ratios were 10 or greater during much of the cloud encounter, indicating that HNO3 may be present in the cloud particles as a stable condensate and not simply physically adsorbed on or trapped in the particles.

Received 27 August 2007; accepted 28 November 2007; published 28 December 2007.

Citation: Popp, P. J., et al. (2007), Condensed-phase nitric acid in a tropical subvisible cirrus cloud, Geophys. Res. Lett., 34, L24812, doi:10.1029/2007GL031832.

Cited By

Please wait one moment ...