HALOE Stratospheric Aerosol Size Distributions
The retrieval of stratospheric aerosol size distributions based on HALOE multi-wavelength particle extinction measurements was described by Hervig et al. . That approach yields unimodal lognormal size distributions, which describe the aerosol concentration versus radius using three parameters: total aerosol concentration, median radius, and distribution width. This site offers results based on the Hervig et al.  technique, with one exception. The retrieval results reported here are based on sulfate refractive indices for 215 K, where Hervig et al.  used room temperature indices adjusted to stratospheric temperatures using the Lorentz-Lorenz rule. Size distributions were only retrieved at altitudes above tropospheric cloud tops. Clouds were identified using techniques described by Hervig and McHugh .
The HALOE size distributions are offered in NetCDF files containing data for a single year. The results are reported on a uniform altitude grid ranging from 6 to 33 km at 0.3 km spacing. The native HALOE altitude spacing is 0.3 km, so this interpolation has little or no effect on the data. The files report profile data including:
altitude, pressure, temperature, aerosol concentration, median radius, distribution width, aerosol composition
Aerosol surface area and volume densities can be easily calculated from the size distribution parameters using the following relationships (IDL code):
vol = (4./3.) * !pi * n1 * r1^3 * exp(9.* alog(s1)^2 / 2.) ; volume in um3/cm3
sfc = (4. ) * !pi * n1 * r1^2 * exp(4.* alog(s1)^2 / 2.) ; surface in um2/cm3
n1 = aerosol concentration (#/cm3)
r1 = median radius (microns)
s1 = distribution width (unitless)
Effective radius can then be calculated as Re = 3.*vol/sfc
The HALOE size distribution data in NetCDF files:1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
IDL subroutine to read the data
Notes:The IDL reader was updated 8 Feb 2005, you'll need it for the new files and it'll work on the old ones.
The data are now complete through Dec 31, 2004.
ReferencesHervig, M. E., T. Deshler, and J. M. Russell III, Aerosol size distributions obtained from HALOE spectral extinction measurements, J. Geophys. Res., 103, 1573-1583, 1998.
Hervig, M., and M. McHugh, Cirrus detection using HALOE measurements, Geophys. Res. Letters, 26, 719-722, 1999.