Summer ‘07 FAMOUS release
(August 22, 2007, at 01:41 PM)
here lives a temporary copy of my notes on the pre-MOSESII.2 tweaked release of FAMOUS. Release will probably officially happen in September or so
Attach:ST_Summer08.png Δ
Attach:STEMP_Summer08.png Δ
| Change | Sci details | Tech Details |
| Ozone | After much experimentation, have ended up with only a minor tweak on the idealised, original FAMOUS 3level O3. The tropopause-finding diagnostic TROPIN is relaxed so as to place the tropopause lower, the “above tropopause” value of O3 specified is slightly lower, and a slightly higher value is then placed in the top model layer everywhere. Everything else tried along the lines of realistic climatologies or more layers looked no better aloft, and frequently had detrimental impacts on the surface temperature. | mods: ozone_mod-3levcustom, tropin11.mod. Replace std. ozone_mod and tropin11 |
| Sea Ice | Much of the northern latitude cold bias is linked to excessive ice production. Encouraging the melting of the ice thus helps. Sea-ice albedo is tempertaure dependent, between a low “melting” value and a high “frozen” value. Here, the melting value has been lowered from 0.5 to 0.2. This is a bit extreme, although individual meltponds may have albedoes this low. A series of values were tried, and this was the best. The overall Northern Hemisphere ice albedo in summer is now a little unrealistically low, but it’s actually better than it was for the rest of the year, and temperatures, year-round, are much improved. There’s also a slight average improvement in the Southern Hemisphere ice coverage. There’s still too much ice cover for much of the year in the Northern Hemisphere, then too little after the summer melt. Interestingly, the excessive ice in the Pacific really isn’t impacted much by this - really, it’s good for the temperatures via the albedo change, rather than by the removel of ice. In addition, the tunable parameter of the minimum ice thickness of 0.5m is also reduced, to 0.25m | Both these changes are specified in the UMUI |
| Orog | The original, less smoothed N24 orography was dusted off and tried - we think the more smoothed version was created to (unsuccessfully) reduce model instabilities, and then never changed back. It’s slightly peakier, and helps both surface temperatures and midlatitude variablility a bit. | ancil: qparm.orog.4837 - reconfigure into atmos dump |
| Orbital variability | a framework is now provided to allow parameters for the orbitally forced seasonalities of different paleo periods to be set. The parameters can either be fixed at a given year, or allowed to vary as time progresses. Varying parameter sets can be “accelerated” by a given factor. The actual parameters are calculated from the model year via either an online calculation, or using published sets of values from extended, offline orbital calculations | mod: calc_solar_params.mod - handedit: orbital_parameters.sh - ancil: solar_params_laskar04 (table of values. Not a UM ancil) |
| Longfilenames/Dates | changes the date convention in the output filenames to allow real paleodates to be used - including negative years. e.g. xbyvra@pyo71c1→ xbyvra#py000002471c1+. Negative years end in “-“ instead of “+”. Currently conv.sh and derivatives can’t cope with negative dates in UM files. | mod: long_output_names.mod - handedit: long_output_names.sh - for full continuation run functioning, some of the small execs need to be rebuilt with this mod as well. The release version should have rebuilt execs supplied with it, apparently. |
| HadOCC | Ocean biogeochemistry that works (?!) in FAMOUS. Can be turned off pretty easily, imposes a ~10% running cost from moving around all the tracers. | mods: alk2.mod, tuning_2.mod, self_shade.mod (parameter tweaks, simple selfshading req’d because the coupled model doesn’t use the banded radiation req’d for the full shading - dump: needs an ocean dump with the tracer fields in i.e. adbip |
