Development of a combined CloudSat‐CALIPSO cloud mask to show global cloud distribution

[1] We developed a cloud mask scheme that combines measurements from CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellites. First, we developed a cloud mask scheme for CALIPSO using a threshold of the attenuated total backscattering coefficient and a spatial continuity test. We then developed a combined CloudSat-CALIPSO cloud mask. These cloud masks were applied to 3 months of data from September to November 2006, and the vertical distributions of zonal mean cloud fractions and cloud coverage were analyzed. We also examined the standard vertical feature mask (VFM) cloud scheme. The VFM occasionally made false detections because of its horizontal averaging procedure and seemed to misclassify noise or aerosols as clouds. In addition, the VFM appeared to significantly overestimate low-level clouds. Below 2 km, the cloud fraction differed by as much as 25% between the VFM and our combined scheme. We also compared the zonal mean cloud coverage for the topmost layer detected by the sensors using our CALIPSO scheme, the VFM, our combined CloudSat-CALIPSO scheme, and the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) results. For low-level clouds (>680 hPa), the MODIS result was larger than that of our CloudSat-CALIPSO scheme, and results from the VFM and our CALIPSO scheme differed by as much as 15%. The CALIPSO, CloudSat-CALIPSO, and MODIS results were similar for total cloud coverage, but the VFM result was different. Because of possible misclassification at low levels, the VFM showed the largest cloud coverage in middle and low latitudes.

[1]  Steven A. Ackerman,et al.  Global Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection and height evaluation using CALIOP , 2008 .

[2]  Hajime Okamoto,et al.  Aerosol retrieval from two-wavelength backscatter and one-wavelength polarization lidar measurement taken during the MR01K02 cruise of the R/V Mirai and evaluation of a global aerosol transport model , 2008 .

[3]  H. Okamoto,et al.  Application of lidar depolarization measurement in the atmospheric boundary layer: Effects of dust and sea‐salt particles , 1999 .

[4]  S. Emori,et al.  Vertical cloud structure observed from shipborne radar and lidar: Midlatitude case study during the MR01/K02 cruise of the research vessel Mirai , 2007 .

[5]  David M. Winker,et al.  Use of probability distribution functions for discriminating between cloud and aerosol in lidar backscatter data , 2004 .

[6]  E. O'connor,et al.  A Technique for Autocalibration of Cloud Lidar , 2004 .

[7]  Andrew A. Lacis,et al.  Global, seasonal cloud variations from satellite radiance measurements. II - Cloud properties and radiative effects , 1990 .

[8]  T. Nakajima,et al.  Wide-Area Determination of Cloud Microphysical Properties from NOAA AVHRR Measurements for FIRE and ASTEX Regions , 1995 .

[9]  S. Solomon.  The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[10]  B. Barkstrom,et al.  Cloud-Radiative Forcing and Climate: Results from the Earth Radiation Budget Experiment , 1989, Science.

[11]  David M. Winker,et al.  Airborne validation of spatial properties measured by the CALIPSO lidar , 2007 .

[12]  Hajime Okamoto,et al.  Global analysis of ice microphysics from CloudSat and CALIPSO: Incorporation of specular reflection in lidar signals , 2010 .

[13]  T. Nakajima,et al.  Vertical cloud properties in the tropical western Pacific Ocean: Validation of the CCSR/NIES/FRCGC GCM by shipborne radar and lidar , 2008 .

[14]  Donald P. Wylie,et al.  Comparison of the Climatologies of High-Level Clouds from HIRS and ISCCP , 1996 .

[15]  Steven Platnick,et al.  A Validation of a Satellite Cloud Retrieval during ASTEX , 1995 .

[16]  Hiroaki Miura,et al.  A Madden-Julian Oscillation Event Realistically Simulated by a Global Cloud-Resolving Model , 2007, Science.

[17]  K. Sassen,et al.  Global distribution of cirrus clouds from CloudSat/Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements , 2008 .

[18]  Hajime Okamoto,et al.  An algorithm for retrieval of cloud microphysics using 95-GHz cloud radar and lidar , 2003 .

[19]  Gerald G. Mace,et al.  Global hydrometeor occurrence as observed by CloudSat: Initial observations from summer 2006 , 2007 .

[20]  Steven A. Ackerman,et al.  Cloud Detection with MODIS. Part II: Validation , 2008 .

[21]  D. Winker,et al.  A height resolved global view of dust aerosols from the first year CALIPSO lidar measurements , 2008 .

[22]  R. Marchand,et al.  A description of hydrometeor layer occurrence statistics derived from the first year of merged Cloudsat and CALIPSO data , 2009 .

[23]  R. Marchand,et al.  Hydrometeor Detection Using Cloudsat—An Earth-Orbiting 94-GHz Cloud Radar , 2008 .

[24]  O. Edenhofer,et al.  Mitigation from a cross-sectoral perspective , 2007 .

[25]  D. Randall,et al.  Mission to planet Earth: Role of clouds and radiation in climate , 1995 .

[26]  J. Spinhirne,et al.  Cloud and aerosol measurements from GLAS: Overview and initial results , 2005 .

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

[28]  D. Jackson,et al.  Trends in Global Cloud Cover in Two Decades of HIRS Observations , 2005 .

[29]  Kenneth Sassen,et al.  Classifying clouds around the globe with the CloudSat radar: 1‐year of results , 2008 .

[30]  Oleg A. Krasnov,et al.  Continuous Evaluation of Cloud Profiles in Seven Operational Models Using Ground-Based Observations , 2007 .

[31]  Simone Tanelli,et al.  CloudSat mission: Performance and early science after the first year of operation , 2008 .

[32]  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 .

[33]  S. Bony,et al.  Comparing clouds and their seasonal variations in 10 atmospheric general circulation models with satellite measurements , 2005 .

[34]  Graeme L. Stephens,et al.  Tropical oceanic cloudiness and the incidence of precipitation: Early results from CloudSat , 2007 .

[35]  W. Paul Menzel,et al.  MODIS Global Cloud-Top Pressure and Amount Estimation: Algorithm Description and Results , 2008 .

[36]  D. Winker,et al.  Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms , 2009 .

[37]  Steven D. Miller,et al.  Rainfall retrieval over the ocean with spaceborne W‐band radar , 2009 .

[38]  E. O'connor,et al.  The CloudSat mission and the A-train: a new dimension of space-based observations of clouds and precipitation , 2002 .

[39]  Tristan S. L'Ecuyer,et al.  The impact of explicit cloud boundary information on ice cloud microphysical property retrievals from infrared radiances , 2003 .

[40]  P. Minnis,et al.  A Climatology of Midlatitude Continental Clouds from the Arm Sgp Central Facility.Part II; Cloud Fraction and Radiative Forcing , 2005 .

[41]  G. Stephens.  Cloud Feedbacks in the Climate System: A Critical Review , 2005 .

[42]  David M. Winker,et al.  CALIPSO lidar observations of the optical properties of Saharan dust: A case study of long‐range transport , 2008 .

[43]  A. Arking,et al.  Retrieval of Cloud Cover Parameters from Multispectral Satellite Images , 1985 .