Version 3.1, 13 February 2013
Streamer is a radiative transfer model that can be used
for computing either radiances (intensities) or irradiances (fluxes) for
a wide variety of atmospheric and surface conditions. Its interface is
very flexible and easy to use. Streamer's major features are:
Fluxes (irradiances) may be computed using two or more streams, either broadband
or narrow band. For more than two streams, a discrete ordinate solver (DISORT)
Radiances (intensities) may be computed for any polar and azimuthal angles,
using 4 or more streams. TOA (top-of-atmosphere) albedos or brightness
temperatures are output along with the radiances.
Upwelling and downwelling, shortwave, longwave, and net fluxes, cloud radiative
effect ("cloud forcing"), and heating rates can be computed.
- There are 24 shortwave and 105 longwave bands.
- Gas absorption is parameterized with overlapping gases. Gaseous absorption
may be turned on or off.
- Liquid and ice cloud optical properties, five aerosol optical models, and
four aerosol vertical profiles are part of the model database. Clouds may be
specified as some combination of particle size, water content, optical and
geometrical thicknesses, or the optical properties and phase function can
be input. A variety of different ice particle shapes (column, aggregate, etc.)
are available. Mixed-phase clouds (liquid and ice or ice and ice) can also
- There are seven standard atmospheric profiles. Either standard or user-defined
profiles can be used, or total column amounts of water vapor, ozone, and/or
aerosols can be specified. Standard profiles include tropical, mid-latitude,
subarctic, and arctic.
- Each computation is done for a "scene", where the scene can be a mixture
of up to 50 individual cloud types occurring individually, up to 50 overlapping
cloud sets, and clear sky.
- Various built-in surface types may occur within the scene: open ocean (sea
water), meltponds, bare ice, snow, vegetation (four types), and dry sand.
Spectral albedo and bidirectional reflectance models (BRDF) are included,
or BRDF data can be input.
- A simple user command language provides looping structures for up to ten variables
at a time, and output can be customized. There is an interactive
(interpreted) mode and a Web interface.
There are, of course, some limitations. How does
Streamer compare to other popular models? Some of the major similarities and
differences are shown in this table.
Processing is controlled by a file that contains a set of options, a set
of input data, and optionally some commands to control printing, variable
reassignment, and looping. Output can be customized.
Streamer is written in standard Fortran 77 and will run on
any platform with a Fortran compiler. Memory usage is small to moderate,
and there are no special hardware requirements.
Version 3 includes DISORT version 2, the capability of specifying a surface
bidirectional reflectance function or a built-in BRDF model, a variety of
ice crystal "habits" (shapes), a facility to
input cloud optical properties including a phase function, the option to compute cloud water content from optical and
geometrical thicknesses, an interactive mode of execution with new commands,
and much more! View the revision
history to see recent changes to Streamer. Note: input files
from version 2 are not compatible with version 3. See the documentation
section for more information.