Studying the vertical variation of cloud droplet effective radius using ship and space-borne remote sensing data

[1] The albedo of marine stratocumuli depends upon cloud liquid water content, droplet effective radius (re), and how these parameters vary with height. Using satellite data and shipborne data from the East Pacific Investigation of Climate (EPIC) Stratocumulus Study, this study investigates the cloud re vertical variation for drizzling and nondrizzling clouds. Visible/near-infrared retrievals from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate the vertical profile of re. MODIS re observations and collocated shipborne scanning C-band precipitation radar data show that re generally increases with height in nondrizzling clouds, consistent with aircraft observations. It is found that in clouds with precipitation rates greater than a few hundredths of a mm h−1 the vertical gradient of re is significantly less than that in nondrizzling clouds and can become negative when the drizzle is heavier than approximately 0.1 mm h−1. High values of re at drizzling cloud base are consistent with estimates of the ratio of liquid water in the drizzle drops to that in the cloud droplets. C-band derived cloud base precipitation rates are found to be better correlated with re at cloud base than with re at cloud top, suggesting that passive remote sensing may be useful for drizzle detection.

[1]  Garik Gutman,et al.  Retrieving microphysical properties near the tops of potential rain clouds by multispectral analysis of AVHRR data , 1994 .

[2]  R. Wood,et al.  Drizzle in Stratiform Boundary Layer Clouds , 2005 .

[3]  Christopher W. Fairall,et al.  Ship-based liquid water path estimates in marine stratocumulus , 2005 .

[4]  L. Schüller,et al.  Radiative Properties of Boundary Layer Clouds: Droplet Effective Radius versus Number Concentration , 2000 .

[5]  Robert Wood,et al.  Drizzle in Stratiform Boundary Layer Clouds. Part II: Microphysical Aspects. , 2005 .

[6]  Robert Wood.  Parametrization of the effect of drizzle upon the droplet effective radius in stratocumulus clouds , 2000 .

[7]  Fuzhong Weng,et al.  Impact of the Vertical Variation of Cloud Droplet Size on the Estimation of Cloud Liquid Water Path and Rain Detection , 2007 .

[8]  H. Gerber,et al.  Microphysics of Marine Stratocumulus Clouds with Two Drizzle Modes , 1996 .

[9]  D. Mechem,et al.  Assessment of variability in continental low stratiform clouds based on observations of radar reflectivity , 2005 .

[10]  Sundar A. Christopher,et al.  Observations of the Global Characteristics and Regional Radiative Effects of Marine Cloud Liquid Water , 1995 .

[11]  W. Paul Menzel,et al.  Cloud and aerosol properties, precipitable water, and profiles of temperature and water vapor from MODIS , 2003, IEEE Trans. Geosci. Remote. Sens..

[12]  B. Stevens,et al.  Observations of Drizzle in Nocturnal Marine Stratocumulus , 2005 .

[13]  D. W. Johnson,et al.  The Measurement and Parameterization of Effective Radius of Droplets in Warm Stratocumulus Clouds , 1994 .

[14]  A. Lacis,et al.  Near-Global Survey of Effective Droplet Radii in Liquid Water Clouds Using ISCCP Data. , 1994 .

[15]  M. King,et al.  Determination of the optical thickness and effective particle radius of clouds from reflected solar , 1990 .

[16]  Henri Sauvageot,et al.  Radar Reflectivity of Cumulus Clouds , 1987 .

[17]  R. Wood,et al.  Drizzle in Stratiform Boundary Layer Clouds. Part I: Vertical and Horizontal Structure , 2005 .

[18]  E. Clothiaux,et al.  Cloud Droplet Size Distributions in Low-Level Stratiform Clouds , 2000 .

[19]  Frank J. Wentz,et al.  Algorithm Theoretical Basis Document (ATBD) AMSR Level 2A Algorithm , 2000 .

[20]  Roy W. Spencer,et al.  SSM/I Rain Retrievals within a Unified All-Weather Ocean Algorithm , 1998 .

[21]  R. Wood,et al.  Cancellation of Aerosol Indirect Effects in Marine Stratocumulus through Cloud Thinning , 2007 .

[22]  Neil I. Fox,et al.  The Retrieval of Stratocumulus Cloud Properties by Ground-Based Cloud Radar , 1997 .

[23]  Bart Geerts,et al.  Identifying drizzle within marine stratus with W-band radar reflectivity , 2003 .

[24]  Takahisa Kobayashi,et al.  Significant differences in the cloud droplet effective radius between nonprecipitating and precipitating clouds , 2007 .

[25]  Qingyuan Han,et al.  Validation of Satellite Retrievals of Cloud Microphysics and Liquid Water Path Using Observations from FIRE. , 1995 .

[26]  Zhanqing Li,et al.  Estimating the vertical variation of cloud droplet effective radius using multispectral near‐infrared satellite measurements , 2002 .

[27]  S. Klein,et al.  The Seasonal Cycle of Low Stratiform Clouds , 1993 .

[28]  Zhanqing Li,et al.  Retrieving vertical profiles of water‐cloud droplet effective radius: Algorithm modification and preliminary application , 2003 .

[29]  Fuzhong Weng,et al.  An eight-year (1987-1994) time series of rainfall, clouds, water vapor, snow cover, and sea ice derived from SSM/I measurements , 1996 .

[30]  C. Bretherton,et al.  Reflectivity and rain rate in and below drizzling stratocumulus , 2004 .

[31]  C. Bretherton,et al.  The Epic 2001 Stratocumulus Study , 2004 .

[32]  Brooks E. Martner,et al.  An Unattended Cloud-Profiling Radar for Use in Climate Research , 1998 .

[33]  B. Albrecht.  Aerosols, Cloud Microphysics, and Fractional Cloudiness , 1989, Science.

[34]  C. Bretherton,et al.  POCKETS OF OPEN CELLS AND DRIZZLE IN MARINE STRATOCUMULUS , 2004 .

[35]  Michael E. Schaepman,et al.  Algorithm theoretical basis document , 2009 .

[36]  James G. Hudson,et al.  Maritime/continental microphysical contrasts in stratus , 2002 .

[37]  Christian D. Kummerow,et al.  Rainfall Climate Regimes: The Relationship of Regional TRMM Rainfall Biases to the Environment , 2006 .