About JACCS

1. Introduction

Clouds play a crucial role in the radiative energy balance and water cycle of the earth-atmosphere system. In order to understand processes such as global warming and to improve assessments of climate change, it is necessary to develop climate models which properly take into account radiation and cloud processes. In addition, it is also important to improve satellite monitoring systems for measuring the global distribution of cloudiness and to derive cloud microphysical properties. The Japanese Cloud-Climate Study (JACCS) is a Japanese research effort focusing on the difficult problems associated with issues related to cloud-radiation interactions. It is one of quasi-decade-long (FY1991-1999) climate research programs sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).

JACCS participants include four national research institutes: the Meteorological Research Institute (MRI) of the Japan Meteorological Agency, the National Research Institute for Earth Science and the Disaster Prevention (NIED) of MEXT, the Communications Research Laboratory (CRL) of the Ministry of Public Management, Home Affairs, Posts and Telecommunications, and National Institute of Advanced Industrial Science and Technology (AIST) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). The Research Steering Committee, chaired by Prof. R. Kimura of the University of Tokyo (1995-), who succeeded Prof. T. Takeda of Nagoya University (1991-1995), guides and promotes the research activities.

Major scientific objectives of the JACCS program are to;

  1. advance our understanding of the relationship between the microphysical properties, the macrophysical cloud structures, and the radiative properties of various clouds;
  2. develop advanced uses of satellite data in the cloud-climate study; and,
  3. develop better parameterizations of cloud and radiation processes used in GCMs.
Research activity involves field observations of clouds and radiation, cloud physics laboratory experiments, satellite data analyses, and numerical modeling of radiation and cloud processes.


2. Outlines of the Study

(1) Experimental Studies on Cloud Microphysical and Radiative Properties

  1. Ground-based observations of high-level ice clouds
    - To accumulate simultaneous observational data on the radiative properties and cloud microphysical properties of cirrus and cirrostratus associated with mid-latitude fronts.
  2. Aircraft observations of low- and mid-level clouds
    - To obtain simultaneous data of the microphysical and macrophysical structures and radiative properties for various mid-latitude low level and mid-level clouds.
  3. Laboratory experiments of the optical properties of cloud particles
    - To study light scattering characteristics of cloud particles.

(2) Satellite Data Analyses

  1. Satellite data analyses of clouds in regional scale
    - To document the climatology of cloud distributions and their variability over the western Pacific region.
  2. Satellite data analyses of clouds on a global scale
    - To derive a satellite cloud climatology of cloudiness and cloud parameters for a validations of GCM cloud parameterizations.

(3) Numerical Modeling of Radiation and Cloud Processes.

  1. Modeling studies of cloud dynamics and structures
    - To study elementary processes of cloud-dynamics and the interactions between cloud ensemble and large-scale motions.
  2. Modeling of radiation processes in cloudy atmospheres
    - To develop several kinds of radiative transfer computational models for realistic atmosphere-cloud-surface systems in both solar and terrestrial radiation spectral regions.
  3. Parameterization of radiation and cloud processes for GCMs.
Contact person : Dr. A. Uchiyama
email: info-jaccs@mri-jma.go.jp
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Revised 31 July, 2003
(Previous revision; 1 October 1999)