Microphysical properties of low clouds over the North Pacific Ocean

Takumi Maruyama, Tadahiro Hayasaka

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Low clouds are widespread over the North Pacific Ocean during summer. Past ship observations, which were carried out in the western region of the North Pacific Ocean, suggested that low clouds (stratus and fog) are likely to occur when sea surface temperature (SST) is lower than surface air temperature (SAT). In this study, we investigated the SST-SAT relationship and microphysical properties of low clouds for the first step of understanding the mechanism of cloud occurrence, maintenance and disappearance by using MODIS satellite observations, JAMSTEC ship observations and MERRA reanalysis data. We divided the North Pacific into four regions according to meteorological condition and made basic statistical analysis about cloud properties in each region by using monthly mean data for July 2011. The statistical analysis indicates that in the central region of the North Pacific where SST-SAT value is negative and the difference is the largest, cloud effective particle radius (re) is larger than those in other regions. We also used ship observation data and simultaneous satellite observation data to examine the relationship between SST-SAT and cloud microphysical properties in detail. This analysis indicates that re in the positive SST-SAT area is larger than that in the negative SSTSAT area. This feature is opposite to the monthly mean results. It suggests that other factors such as humidity and aerosols as well as SST-SAT have to be taken into account, although the SST-SAT relationship can be one of the important factors determining cloud microphysical properties in the summer North Pacific region.

Original languageEnglish
Title of host publicationRemote Sensing of the Atmosphere, Clouds, and Precipitation IV
Publication statusPublished - 2012
EventRemote Sensing of the Atmosphere, Clouds, and Precipitation IV - Kyoto, Japan
Duration: 2012 Oct 292012 Oct 31

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceRemote Sensing of the Atmosphere, Clouds, and Precipitation IV


  • cloud microphysical properties
  • low clouds
  • North Pacific
  • SAT
  • SST


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