!Robin Smith
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'''[++Current Issues in FAMOUS++]'''
I'm trying to keep up incrementally with new developments under the relevant subject headings, so check back on those specific pages and look for the changes (either in the Solution section, or at the top of the page) if you're interested in a specific issue. Anything urgent will also be flagged up here.
Standard/Release version of FAMOUS have their own changelogs at [[FAMOUSStandardVersions]].
Datestamps under the headings indicate the last modification time of that section.
Any technical details refer to my filenames only - these may well be changed/combined with others in release versions.
If anyone's actually reading this and would like to be able to track developments in a more obvious manner, let me know.
r.s.smith at reading.ac.uk
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!!! Miscellaneous
'''Dec. '08'''
-> update on the self_shade issue: doesn't look like running with the old self_shade mod but without [=HadOCC=] (e.g. xcpsb) has any significant effect on the climate. One test run did show a small coupling shock at going from the broken->fixed parameterisation, but there was very little difference once the climate had settled down.
-> an interesting development in timestepping. Ron Kahana at Bristol has been running with two dynamic sweeps per timesteps in the atmosphere to help with stability. I've done some tests, and it turns out that this significantly affects the mean climate, cooling the tropics and warming the poles. It's not really clear yet why. If used with the re-tuned ice albedoes of xcpsb and later, this gives you a rather large warm bias over the Arctic, compared to xcpsb/xdbua. Used with the original ice albedo values though, two sweeps seems to bring surface temperatures closer to those in [=HadCM3=], and also improves northern hemisphere seasonality.
-> I'm continuing tests with lower isopycnal diffusion in the ocean, along with free-drifting ice. These two seem to help the Southern Ocean warm bias and increase AABW. The grand plan now is to (manually) tune the sea-ice again using these, along with the snow_on_ice bugfix (see July), and 2 dynamic sweeps in the atmosphere for a hopefully even better FAMOUS.
-> yes, it's ''another'' '''BUG WARNING'''. MOSES1 [=FAMOUSes=], up to and including xcpsa and xdbub, appear to have their grid box mean surface sensible heat and moisture fluxes swapped for ocean and coastal points at the end of SFFLUX5A.F. Surface climate affects appear to be pretty small, patches of cooling of around a degree in the northern hemisphere in winter. I've a new version of the coastal tiling mod ctile_09_new_param, that will be included in future releases, but I'm not planning to backdate it. As for the ancil bug below (see November), this isn't an issue in MOSES2.
'''Nov. '08'''
-> another '''BUG WARNING''', although hopefully this won't affect anybody at all. It seems that '''the ancil system in UM4.5 does not correctly update land ancils during a run'''. I'm guessing no-one is affected by this, as no-one's complained about it yet - I've only found it from trying to do long transient paleo runs. The model doesn't necessarily crash, but it's pretty clear that things have gone wrong. This only affects MOSES1 - MOSES2 FAMOUS has this issue fixed. I have a mod for MOSES1 now - let me know if you'd like it.
-> many small things are being tested, probably none will make it into a release: wider Drake Passage, deeper Drake Passage, lower ocean isopycnal diffusivity, free-drifting ice...
* Am pretty sure that the piston velocity thing below ''isn't'' the main problem in the free CO2 crashes - it just causes the climate to segfault rather than run on, madly, for a few years. Can't prove it, but a few things point to simple numerical instability in the tracer transport scheme which deals with the CO2 in the atmosphere. All seems OK in runs with better spun-up climates, so the caveat remains - don't try to do spin-ups with free atmospheric CO2. Transients and the like may need smaller atmospheric timesteps to cope with this issue.
* '''BUG WARNING:''' if your model is compiled with the ''self_shade.mod'' but [=HadOCC=] is turned off - '''this applies to release xcps[abc]'''. This mod deals with absoption of solar radiation at the top of the ocean, and we've found that it assumes that [=HadOCC=] is enabled. It's not yet clear what the impact is of using the code with [=HadOCC=] off. There might also conceivably be implications for the stability of the model. My personal guess is that it's not a big deal, but I'll provide more information as we get it.
* if anyone's using any of the proto-MOSES2 jobs with TRIFFID off, they need an extra ancil to do seasonal leaf/canopy changes. This will be included in the soon-to-be-released MOSES2 testing job. Including the ancil doesn't help the unpleasant temperature biases much though.
'''Sept. '08'''
->'''brief note''': you may have heard me complaining over the past 6+ months of a mysterious segfault problem with MOSES2.2+free CO2 runs, and, earlier, of free CO2 runs exploding with physically impossible levels of atmospheric CO2. I ''think'' I've sorted both of these issues now, both of which were traced to the calculation of the piston velocity for air-sea CO2 exchange operating outside its valid range while the warm MOSES2.2 climate spins up. I've put a couple of numerical caps into the formula, which shouldn't affect "normal" runs at all. It's probably not a good idea to attempt to spin up a completely new climate state with free atmospheric CO2 anyway, far too much potential for things to go wrong...
'''July '08'''
-> I appear to have neglected this page slightly - mostly a result of doing too many little things at once, none of which were quite worth writing up. So, new things with FAMOUS:
*I've been spinning up the UTOPIA biogeochem MOSES1 FAMOUS, and have about 5000 years worth now. I've recalculated the iceberg flux for this run now and the salinity drift is now pretty small - there's still drift in the ~2441 era dump runs as the climate settles down, even with the iceberg flux there.
*this spun-up MOSES1 FAMOUS has been written up for the new EGU journal Geoscientific Model Development. You can read the draft, and make comments via [[http://www.geosci-model-dev-discuss.net/1/147/2008/gmdd-1-147-2008.html|the GMD discussion forum]] - please take a look.
*given that the MOSES2.2 climate is still not great, I've worked up a version of MOSES1 FAMOUS which allows you to have interactive atmospheric CO2 via exchange with the ocean (land fluxes are 0 by default, or can be specified via the CO2 emissions ancil) - oddly enough, this isn't allowed by the standard UMUI config. I've got about 1000 years of "free CO2" MOSES1 FAMOUS that I haven't looked at, but hasn't crashed!
*a long-standing error in the UM4.5 coupling routines has been discovered and fixed. All versions of FAMOUS until now have had snow cover on land at coastal points overwritten by the snow depth on sea-ice every coupling step. It's unclear what impact this has had - any salinity drift in the ocean has been corrected by the iceberg flux anyway. Fix mods wil be included in release downloads soon, or contact me for pre-release versions if you're desperate. Thanks to Ron for bringing the issue to our attention.
->'''impacts:''' fixing this has a larger impact than I expected. Global mean surface T comes down by half a degree or so, which is nearly all due to cooling along the coasts of Greenland and Antartica, with up to 2 degrees drop in zonal mean surface temp. north of 40N. Zonal surface temp deviations from HadCM3 are still far more like XBYVA than ADTAN though. There's a rather small increase in annual mean ice concentration. Quite a few of the coastal areas of Greenland and Antarctica look like they are successfully supporting significant snow amounts now, it's not that the snow is just being lost at a slower rate. There's an increase in freshwater input to the ocean amounting to an extra freshening rate of ~0.004 psu per century in this run, but this may be a short term result of having reset all the land snow to 50,000 kg/m^2 over ice and there being some extra melt as things come back into equilibrium.
*FAMOUS workshop 2008. If you're reading this, you almost certainly know about this already, but if not the workshop will happen on '''August 29th in Reading''' - let me know if you'd like to attend.
*FAMOUS on QUEST is having more, subtle, reproduceability issues. Recompiling can sometimes change your results. Currently a mystery.
'''April '08'''
-> there's a valnote up for the fully carbon-cycling FAMOUS at [[http://www.met.reading.ac.uk/~robin/valnote/MOSES2.2_Int/plots.html]]. It's still too warm; someone, somewhere will probably have to do some tuning. Officially, time is up on the NCAS FAMOUS development work, so this is the "release" version of MOSES2.2 FAMOUS. Practically, work continues...I've started to put up some notes on the differences in climate between MOSES1 and MOSES2.2 versions on my [[CurrentWorkIntCO2|Interactive CO2 ]] page.
'''March '08'''
-> back to work after our first baby. UTOPIA fields are pretty much spun up now, as global CO2 fluxes are <<0.2GtC/yr and look much better than before. Development work will now concentrate on the differences produced going from MOSES1 to MOSES2.2. MOSES2.2 is a lot drier (which is probably a good thing, as MOSES1 was waterlogged) but a fair bit warmer (which is not such a good thing) - so currently the coupled carbon FAMOUS runs have quite a different surface climate to the Dec07 release.
-> a minor pitfall: although Dec07 FAMOUS includes HadOCC, there's no coupling of CO2 values between ocean and atmosphere - if you don't have a fully interactive carbon cycle (MOSES2.2, TRIFFID, 3d field in atmosphere etc), the atmospheric pCO2 seen by the ocean is set in the UMUI independently of that set for the atmosphere. The default, static values in the UMUI set both to be the same, which is fine as long as you don't change one. '''If you specify a changing atmospheric pCO2 value (say, a 1% increase) in the UMUI, the ocean biogeochemistry will not see the increase in CO2'''. I have a mod that fixes this now, let me know if you need it.
'''January '08'''
-> The ocean CO2 flux fields in Dec07 FAMOUS don't look too great - in general the fluxes are too large, with some large outgassing patches in the SO and N.Atlantic. A few thousand years of spinup and CO2 outgassing is still going on, although at less than 0.2GtC/yr, which is where the [=MetOffice=] decided to call their [=HadCM3LC=] runs "steady". Ian Totterdell recommended the use of the flux-limited UTOPIA advection scheme for the biogeochem tracers, which is what they use in more recent versions of [=HadOCC=], and I've finally got hold of some mods for this. I've made versions that seem to work with FAMOUS, and I'm trialling them now.
-> A number of people pointed out reproduceability and STASH issues on QUEST at the end of last year. We've been running various tests, and QUEST is definitely more of a problem than HPCx was. All the problems we've found so far can be alleviated by removing compiler optimisation on QUEST (just use -i8 -r8 -O0 -Kieee for compiler options), but this seriously slows the model down. More selective de-optimisation is under investigation by Annette et al. - I've left this one to the professionals!
-> UPDATE: Flux-limited UTOPIA advection of biogeochemical tracers really improves the CO2 flux fields and brings them back to something believable. It still needs spinning up quite a bit more though, so it'll be a while before there's a good ocean state to release. Also, Annette and Simon have been working on the bit-reproduceability issues on QUEST and other platforms, with a fair degree of success. There's a mod, some compiler options and a new version of gcom that will be incorporated into the standard version soon - FAMOUS should now be bit reproduceable on QUEST across different processor configurations and across CRUN restarts.
'''December '07'''
-> Finally, the Summer Release is being released. It's not perfect, but you've got to stop somewhere. See the [[FAMOUSStandardVersions]] pages. The documentation that I've put up for this ([[Dec07]]) is basically the same as the Summer07 stuff, but things that needed extensive handediting then have now been incorporated into the UMUI properly. I'm more than happy to answer queries and provide help, but it's probably more transparent all round if questions get routed through the [[http://ncas-cms.nerc.ac.uk/trac/UMHelpdesk|helpdesk]], so they can be logged and tracked properly.
'''October '07'''
-> Having been on a few trips and cleared up a few bugs, the "Summer 07 Release" of FAMOUS is now ready (see entry for August)! '''Release documention (science changes) can be found at the [[Summer07| Summer 07 Release Page]]'''. Files will be available on [[http://ncas-cms.nerc.ac.uk/content/view/736/187|PUMA]] somehow, sometime soon, via Annette, or email me.
-> MOSESII.2 finally runs! Assessment/tuning work will be logged in the new [[CurrentWorkMOSES|MOSES]] section below.
'''September '07'''
-> Following a suggestion of Jonathan's, I've run up a simple script to subdivide the climate up into the Koeppen zones, to give an indication of where errors might impact the vegetation most. Compared to both [=HadCM3=], and observations (the plot below includes ERA data run through my script, which doesn't match up perfectly with the published "observations" anyway) we're looking pretty good, to my eyes at least.
%center%[[http://www.famous.ac.uk/Figures/Koeppen.eps|Attach:Koeppen.gif]]
'''August '07'''
-> Jonathan and I have decided to do a new release of FAMOUS, with all my current climate mods in, before we incorporate all the recoding Annette's been doing for the MOSESII.2 version. In addition to the salinity drift cancellation mod (vflux_drift), this will have new sea-ice albedoes (improved Nhemisphere surface temps), modified - but still idealised - ozone (improved high altitude temps), less smooth orography (improved surface temps, jet stream EKE) and options for different orbital parameters and a verylong filename convention.
'''July '07'''
-> I've followed up Ken Caldeira's suggestion of swapping the order of the filtering and convection subroutines in the ocean to improve stability. There is now a mod that compiles and runs - I don't really have problems with crashes in the ocean, so I can't tell whether it's improved anything. If anyone's got a problem they think this might help with, let me know so I can pass it on.
-> I've done a brief run with a less-smoothed 48x37 orography - the current, smoothed version was originally introduced into FAMOUS to try to remove some instabilities that used to exist. I've only run a few decades, but I have no instabilities and slightly improved surface temperature and eddy kinetic energy stats. from the rougher, occasionally higher surface.
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!!![[CurrentWorkOzone | Ozone]]
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!!![[CurrentWorkSalinitydrift | Salinity Drift]]
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'''April '07'''
-> The salinity drift code has been revised to STASH the correction in more helpful units for the post-diagnosing of tendencies. A number of small bugs have been found in the version currently in xbyvs, but they only affect accuracy by a % or so. The new version also applies the correction to the TCO2 and Alk fields to reduce spurious drift in those fields.'''This new version is included in release xcggb, which is now recommended over xbyvs.'''
'''June '07'''
-> Wouldn't you know it, a fairly catastrophic bug has been found living in the above, "bug-fixed" mod. Don't use vflux_drift.mod without [=HadOCC=] enabled. '''Now fixed - only use vflux_drift.mod_xcggb version.'''
!!! [[CurrentWorkColdBias | Cold bias]]
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!!![[CurrentWorkHadOCC | Marine Biogeochemistry]]
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!!![[CurrentWorkPaleo | Paleo Forcing Issues]]
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!!![[CurrentWorkMOSES | MOSESII.2 ]]
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!!![[CurrentWorkIntCO2 | Interactive CO2 ]]
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