Small, highly reflective ice crystals in low‐latitude cirrus

[1] At low latitudes, cirrus are ubiquitous and can be in excess of 100°C colder than the surface, limiting the amount of sunlight absorbed by the earth's atmosphere and surface, and reducing its loss of heat. Here we present aircraft measurements within cirrus over southern Florida indicating that ice crystals have smaller sizes and are more reflective than is assumed in most current climate models. If the measurements are generally representative of low-latitude cirrus, they point to a first-order correction to representations of how these clouds affect the earth's climate.

[1]  George A. Isaac,et al.  Ice particle habits in Arctic clouds , 1999 .

[2]  Paul W. Stackhouse,et al.  The Relevance of the Microphysical and Radiative Properties of Cirrus Clouds to Climate and Climatic Feedback , 1990 .

[3]  James J. Hack,et al.  Response of Climate Simulation to a New Convective Parameterization in the National Center for Atmospheric Research Community Climate Model (CCM3) , 1998 .

[4]  J. Foot,et al.  Some observations of the optical properties of clouds. II: Cirrus , 1988 .

[5]  H. Gerber,et al.  Nephelometer Measurements of the Asymmetry Parameter, Volume Extinction Coefficient, and Backscatter Ratio in Arctic Clouds , 2000 .

[6]  Pi-Huan Wang,et al.  CRISTA observations of cirrus clouds around the tropopause , 2002 .

[7]  J. Wilson,et al.  Measurements of high number densities of ice crystals in the tops of tropical cumulonimbus , 1993 .

[8]  H. Jonsson,et al.  The cloud, aerosol and precipitation spectrometer: a new instrument for cloud investigations , 2001 .

[9]  M. Wendisch,et al.  Performance of a Counterflow Virtual Impactor in the NASA Icing Research Tunnel , 2003 .

[10]  George A. Isaac,et al.  Parameterization of effective ice particle size for high‐latitude clouds , 2002 .

[11]  K. Liou,et al.  Single-scattering properties of complex ice crystals in terrestrial atmosphere , 1998 .

[12]  Stefan Kinne,et al.  Tropical cirrus cloud radiative forcing: Sensitivity studies , 1994 .

[13]  Richard C. J. Somerville,et al.  SCM Simulations of Tropical Ice Clouds Using Observationally Based Parameterizations of Microphysics , 2003 .

[14]  David L. Mitchell,et al.  Modeling cirrus clouds. Part II: Treatment of radiative properties , 1996 .

[15]  J. Key,et al.  Tools for Atmospheric Radiative Transfer: Streamer and FluxNet. Revised , 1998 .

[16]  S. Bony,et al.  Combining ERBE and ISCCP data to assess clouds in the Hadley Centre, ECMWF and LMD atmospheric climate models , 2001 .

[17]  C. Twohy,et al.  Measurement of Condensed Water Content in Liquid and Ice Clouds Using an Airborne Counterflow Virtual Impactor , 1997 .

[18]  H. Gerber,et al.  Shortwave, single‐scattering properties of arctic ice clouds , 2001 .

[19]  J. Gayet,et al.  In Situ Observation of Cirrus Scattering Phase Functions with 22° and 46° Halos: Cloud Field Study on 19 February 1998 , 2001 .

[20]  K. Liou,et al.  Solar Radiative Transfer in Cirrus Clouds. Part I: Single-Scattering and Optical Properties of Hexagonal Ice Crystals , 1989 .

[21]  Robert J. Curran,et al.  Thin cirrus clouds - Seasonal distribution over oceans deduced from Nimbus-4 IRIS , 1988 .

[22]  Andrew J. Heymsfield,et al.  High Albedos of Cirrus in the Tropical Pacific Warm Pool: Microphysical Interpretations from CEPEX and from Kwajalein, Marshall Islands , 1996 .

[23]  E. Weinstock,et al.  New fast response photofragment fluorescence hygrometer for use on the NASA ER‐2 and the Perseus remotely piloted aircraft , 1994 .

[24]  W. Weaver,et al.  Two-Stream Approximations to Radiative Transfer in Planetary Atmospheres: A Unified Description of Existing Methods and a New Improvement , 1980 .

[25]  D. Hartmann,et al.  The Effect of Cloud Type on Earth's Energy Balance: Global Analysis , 1992 .

[26]  David L. Mitchell,et al.  Impact of a new scheme for optical properties of ice crystals on climates of two GCMs , 2000 .

[27]  Christopher P. Weaver,et al.  Improved Techniques for Evaluating GCM Cloudiness Applied to the NCAR CCM3 , 2001 .

[28]  P. Chylek,et al.  Infrared Emittance of Water Clouds , 1992 .

[29]  John Hallett,et al.  Degradation of In-Cloud Forward Scattering Spectrometer Probe Measurements in the Presence of Ice Particles , 1985 .

[30]  M. Mishchenko,et al.  The influence of inclusions on light scattering by large ice particles , 1996 .

[31]  J. Foot,et al.  Some observations of the optical properties of clouds , 2006 .

[32]  U. Lohmann,et al.  A parameterization of cirrus cloud formation: Homogeneous freezing of supercooled aerosols , 2002 .

[33]  Ping Yang,et al.  The Distribution of Tropical Thin Cirrus Clouds Inferred from Terra MODIS Data , 2003 .