## 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. [1998]. 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.
[1998] technique, with one exception. The retrieval results
reported here are based on sulfate refractive indices for 215 K,
where Hervig et al. [1998] 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 [1999]. 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 where 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, 2005IDL 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. |