Dynamic tropopause

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Diagnostics

There are

Previous issues that are now resolved

Buggy implementation in v7-04-12

Note that the implementation of the variable tropopause is buggy in versions prior to GEOS-Chem v7-04-12. If you are using versions prior to v7-04-12, you should turn the variable tropopause OFF.

Polar cap

Jennifer Logan (see correspondence below) suggested that we should cap the variable tropopause at 200hPa in near-polar regions (90-60S and 60-90N), to avoid the problem with anomalously high tropopause heights at high latitudes. This fix was standardized in GEOS-Chem v7-04-13.

Jennifer Logan wrote:

After looking at the two papers I sent, I think we should restrict the tropopause at latitudes > 60 deg. to pressures greater than 200 mb (about 11 km). From Fig. 3 in Seidel and Randel, there are tropopause (TP) heights as high as 13.5 km in the Antarctic (median height is ~9.8 km, 250 mb), but I don't think we want to be doing trop. chem there. The median TP pressure at ~80 N is ~300 mb, compared to ~250 mb at 70-85 S. The extratropical TP heights are higher (lower pressure) in the SH than in the NH according to Fig. 3.

This approach is also very easy to explain in a paper.

Jennifer

Problem reading GEOS-4 TROPP files

Dave MacKenzie wrote:

We encountered an I/O Error 29 with file 69 when trying to run GEOS4 v8-01-01 with the variable tropopause turned on at 4x5 resolution. When I investigated this problem further, I found that there was no code written to copy and unzip the YYYYMMDD.tropp.4x5.gz files. Since I didn't see any mention of this online for v8-01-01 or newer versions, I thought I should bring it to your attention.

The *.tropp* files are accessed in i6_read_mod.f but there is only code included to use the data in those files and erase them from the TEMP directory. No code was included to actually copy them into the TEMP directory and unzip them. I wrote in a few lines of code and our problems disappeared. After running the code for one day, it finished smoothly with no problems. Then I tried running it for 2 years and it crashed after two months (I/O error 67 in file 72, input statement requires too much data). I don't know if it's a related problem to the changes I made or something else, but I thought I'd bring this to your attention. Thanks!

Bob Yantosca replied:

Yes...the TROPP files for GEOS-4 were an afterthought. We have always stored the GEOS-4 data as uncompressed, in order to avoid the problem. That might be a good solution if you have the disk space.

--Bob Y. 16:44, 18 February 2009 (EST)

Outstanding issues

--Bob Y. 12:44, 13 September 2010 (EDT)