Updated on Sept. 5, 2003
CPEA (Coupling Process of Equatorial Atmosphere)
Grant-in-Aid Scientific Research on Priority Areas CPEA (A03 Subgroup)
in collaboration between Japan and Indonesia
Study of Equatorial Convective Activity: Generation and Evolution
- Background of Research
$B!!(BThe Maritime Continent is known as the area having the most active convection in the world. This active convection plays the role of the "heat engine" which carries the thermal energy of earth surface to upper troposhere, influencing the global climate and weather patterns.
Therefore, understanding of convective activity and its relationships to larger-scale atmospheric phenomena are crucial for the elucidation of regional to global atmosphere.
$B!!(BFurthermore, the active convection in this area should generate equatorial, gravity waves which influence upper atmospheric regions such as stratosphere$B!%(BThe momentum transport by the wave motion may control atmospheric circulation of the equatorial region up to the altitude of around 100 km, also influencing theglobal climate.
$B!!(BTo understand the vertical structrure of the atmosphere, observations of various atmospheric parameters such as wind, temperature, and humidity are necessary, in addition to the rainfall distribution observed by a rain rader.
Moreover, in order to clarify seasonal to annual variation of convective activities, long-term and continuous observations are required.
In 2000, the Equatorial Atmosphere Radar (EAR) was successfully constructed at Koto Tabang, west Sumatra, by RASC, Kyoto University and LAPAN, Indonesia. Since then observation systems has become more and more comprehensive. The CPEA project aims at further progresses of the study of equatorial atmosphere from the lower-to-upper atmospheric coupling point of view.
The CPEA-A03 subgroup has a role to cover the lower-most atmospheric region, i.e. convective activity and related atmospheric phenomena of this region.
- Reserch Purpose
The objective of this project (A03 subgroup) is to understand the behavior and mechanisms of convection-origin atmospheric waves as well as the hierarchical structure of equatorial convective activities and couplings between them, through comprehensive observations of equatorial atmosphere utilizing the EAR (Equatorial Atmosphere Radar) and various instruments.
It is therefore important to construct and maintain reliable observation and data quality to contribute to scientific studies.
- Present Status and Research Plan
$B!!(BThe research plan of an outline is shown in the right figure.
In 2001, several instruments for simultaneous observations with the EAR; i.e. a water-vapor profiling radiometer (WVP-1500), an optical raingage (ORG-815), three microbarographs, a micro-rain radar (MRR-2) and a test instumentation of the RASS (Radio Acoustic Sounding System) combined with the EAR, have been nstalled and entered the operation.
In 2002, an X-band scanning rain radar (X-radar) and a video disdrometer (2DVD) have been installed in addition to the continuous tests of the RASS. By the end of FY 2002 (i.e. the end of March 2003), all instruments (except a "full" RASS) have entered regular operations and data are continuously collected. These data are periodically transfered to RASC and Shimane University and browse images are up-loaded on our web sites.
We also plan to install an X-band Doppler radar (ILTS, Hokkaido University) near the EAR site during the intensive campaign periods scheduled in March-April 2004 and November 2005. The preparation is on-going by the close cooperation between Japan and Indonesia (LAPAN).
In the area of science research, we have started free-discussions with related scientists in Japan and Indonesia to organize a kind of "broad" science group members of which consists of various aspects of equatorial convective activities; cloud microphysics, kinematic mechanism of each convective cell, mesoscale to global-scale phenomena, and wave generation and momentum transport. After that various preparatory studies have been started on tropical rainfall characteristics not only around Koto Tabang but including global tropics.
Since the start of regular observations at Koto Tabang along with the EAR, several preliminary but interesting results have been obtained and presented at various scientific meetings. We are now preparing to publish these results on scientific journals.
Scientific planning of the coming intensive observation campaign mentioned above is also among the important tasks of the science group.
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