Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Droplet size spectra and water-vapor concentration of laboratory water clouds: inversion of Fourier transform infrared (500–5000 cm-1) optical-depth measurement

Not Accessible

Your library or personal account may give you access

Abstract

Infrared extinction optical depth (500–5000 cm-1) has been measured with a Fourier transform infrared spectrometer for clouds produced with an ultrasonic nebulizer. Direct measurement of the cloud droplet size spectra agree with size spectra retrieved from inversion of the extinction measurements. Both indicate that the range of droplet sizes is 1–14 µm. The retrieval was accomplished with an iterative algorithm that simultaneously obtains water-vapor concentration. The basis set of droplet extinction functions are computed once by using numerical integration of the Lorenz–Mie theory over narrow size bins, and a measured water-vapor extinction curve was used. Extinction and size spectra are measured and computed for both steady-state and dissipating clouds. It is demonstrated that anomalous diffraction theory produces relatively poor droplet size and synthetic extinction spectra and that extinction measurements are helpful in assessing the validity of various theories. Calculations of cloud liquid-water content from retrieved size distributions agree with a parameterization based on optical-depth measurements at a wave number of 906 cm-1 for clouds that satisfy the size spectral range assumptions of the parameterization. Significance of droplet and vapor contribution to the total optical depth is used to evaluate the reliability of spectral inversions.

© 1997 Optical Society of America

Full Article  |  PDF Article
More Like This
Observation of Raman scattering by cloud droplets in the atmosphere

S. Harvey Melfi, Keith D. Evans, Jing Li, David Whiteman, Richard Ferrare, and Geary Schwemmer
Appl. Opt. 36(15) 3551-3559 (1997)

Infrared and visible Fourier-transform spectra of sulfuric-acid–water aerosols at 230 and 294 K

Adam E. Heathfield, David A. Newnham, John Ballard, Roy G. Grainger, and Alyn Lambert
Appl. Opt. 38(30) 6408-6420 (1999)

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Figures (14)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Tables (1)

You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Equations (6)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved