3-D polarised simulations of space-borne passive mm/sub-mm midlatitude cirrus observations: a case study C. P. Davis1, K. F. Evans2, S. A. Buehler3, D. L. Wu4, and H. C. Pumphrey1 1Institute of Atmospheric and Environmental Science, University of Edinburgh, Edinburgh, UK 2Dept. of Atmosphere and Oceanic Sciences, University of Colorado, Boulder, USA 3Department of Space Science, Lulea Technical University, Kiruna, Sweden 4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
Abstract. Global observations of ice clouds
are needed to improve our understanding of their
impact on earth's radiation balance and the water-cycle.
Passive mm/sub-mm has some advantages compared to other space-borne
cloud-ice remote sensing techniques. The physics of scattering makes
forward radiative transfer modelling for such instruments challenging.
This paper demonstrates the ability of a recently developed RT code,
ARTS-MC, to accurately simulate
observations of this type for a variety of
viewing geometries corresponding to operational (AMSU-B, EOS-MLS) and
proposed (CIWSIR) instruments.
ARTS-MC employs an adjoint Monte-Carlo method, makes
proper account of polarisation, and uses 3-D spherical geometry. The
actual field of view characteristics for each instrument are also
accounted for. A 3-D midlatitude cirrus scenario is used, which
is derived from Chilbolton cloud radar data and a stochastic method
for generating 3-D ice water content fields.
These demonstration simulations clearly demonstrate the
beamfilling effect, significant polarisation effects for
non-spherical particles, and also a beamfilling effect with regard to
Citation: Davis, C. P., Evans, K. F., Buehler, S. A., Wu, D. L., and Pumphrey, H. C.: 3-D polarised simulations of space-borne passive mm/sub-mm midlatitude cirrus observations: a case study, Atmos. Chem. Phys., 7, 4149-4158, doi:10.5194/acp-7-4149-2007, 2007.