Report on the joint US-Japanese workshop on "Coupling of the Troposphere and Stratosphere by Dynamical, Radiative and Chemical Processes",
Kyoto, Japan, 13-17 March, 2001

William Randel, NCAR, Boulder, USA (randel@ucar.edu)
Shigeo Yoden, Kyoto University, Japan (yoden@kugi.kyoto-u.ac.jp)

This workshop was jointly sponsored by the Japanese Society for the Promotion of Science and the US National Science Foundation, with additional support from the Japanese Ministry of Education, Culture, Sports, Science and Technology (Grant-in-Aid for Scientific Research on 'Stratospheric Variations and Climate') and the Kyoto University Foundation. The workshop was arranged on the occasion of the retirement of Professor Isamu Hirota from Kyoto University, and jointly organised by Shigeo Yoden (Kyoto University) and William Randel (National Center for Atmospheric Research). A web page discussing the workshop program can be found at http://www-mete.kugi.kyoto-u.ac.jp/Kyoto2001/index.htm

Dynamical links between the troposphere and stratosphere are inevitably two-way. Several kinds of waves generated in the troposphere propagate into the stratosphere and interact with the mean flow, while the stratospheric circulation also has influences on the large-scale flow in the troposphere. Radiative, chemical and transport processes (such as ozone transported across the mid-latitude tropopause) are also important for coupling these regions. Although mean structure and variability have sometimes been investigated separately in the troposphere and middle atmosphere research communities, the importance of coupling is becoming more evident in data analysis and modelling studies.

The main objective of the workshop was to foster continued collaborations between Japanese and US scientists involved in stratospheric and tropospheric research, with a focus on studying mechanisms which couple the two regions over a broad range of time scales. The participants consisted of a number of Japanese and US researchers (approximately 15 from each country), plus a few scientists from Canada, Europe, Asia and Australia. Also included were a number of younger (postdoctoral-level) Japanese and US scientists. The workshop was organised according to the themes of:

- Overviews and General Circulation Model studies
- Transport and chemistry
- Wave processes
- Intraseasonal and interannual variability

In between four full days of invited lectures covering the preceding topics, one day was devoted to a morning of presentations by young scientists combined with an afternoon celebrating 'Professor Hirota and his old friends'. The morning lectures were arranged in the form of alternating Japanese and US talks, with friendly competetitive 'matches'. The afternoon featured talks by Professors Taroh Matsuno, Mike Wallace, Hiroshi Yanaka, Jim Holton, Susumu Kato, Alan Plumb, Saburo Miyahara and Matt Hitchman reminiscing on the career of Professor Hirota, including highlighting his pioneering research and original contributions on the general circulation and waves in the middle atmosphere. Later, Professor Hirota gave a keynote presentation on the 'Early days of equatorial middle atmosphere studies: personal retrospective', providing a unique perspective on the leading scientists and important early discoveries in middle atmospheric science. Finally the entire conference shared a traditional Japanese dinner at a Zen-style Tofu restaurant.

A written proceedings of this workshop will take the form of a special issue of the Journal of the Meteorological Society of Japan, containing review papers or original research articles from each of the workshop participants, with a publication date of early 2002. Overall the workshop exceeded expectations in terms of combining high quality science with many opportunities for interactions, all in the historic setting of Kyoto. This workshop will serve as a lasting tribute to the distinguished career of Professor Hirota.

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