4DVAR physics minutes 07/07/06

10:20-10:50 7/7/06 Lilly room

Participants: Hans, Jimy, Qingnong

1. Simple vertical diffusion

Qingnong has made the TL and AD for the simple vertical diffusion. They are in the current 4D-Var system.

Jimy wants to make sure which module has been touched. His guess is big_step.

There has been a discussion on how to follow the Buizza approach. Jimy suggests to try an even simpler approach.

Action: Hans will work with Jimy to test his simple approach. Start next week.

2. Other physics TL and AD

Qingnong has started re-organizing nonlinear physics subroutines. The re-organized subroutines should reproduce the results from the original subroutines.

Jimy's advices are needed when simplifications are necessary. Jimy agreed to help.

Furthermore, Jimy also agreed to help Hans and Qingnong select physics subrountines or even create a new, simple "large scale condensation" subroutine, suiable for 45km 4D-Var innerloop.

There are different requirements from operational side (e.g. AFWA) and research side. Qingnong already made the TL and AD for a simple microphysics scheme. Hans hope to use it in the WRF TL and AD. In the same time, Qingnong and his visitor, Liqiang Chen, are working on the TL and AD of a more sophisticated microphisics scheme.

Action: Qingnong will create a list of physics subroutines for TAF. A complete physics package for 4D-Var should be generated by TAF by the end of this year. Hans will check with John whether the calls to physics are preserved in his new TAF-generated code.