| 195 | | |
| | 195 | |
| | 196 | ''' Fuxing Wang, Fréderique Chéruy, Agnès Ducharne, Jan Polcher, Philippe Peylin, et al. 11/02/15 (mail)''' |
| | 197 | |
| | 198 | ''Topic:'' [[BR]] |
| | 199 | Oscillations in the ORCHIDEE-LMDZ coupled model with the revised soil thermodynamics.[[BR]] |
| | 200 | ''Background'': [[BR]] |
| | 201 | There are mainly three modifications in the soil thermal process. [[BR]] |
| | 202 | (1) In the current ORC, different soil vertical layers are used for hydrology (11 layers, 2-meter) and thermal (7 layers, around 5-meter). In the revised one, the same vertical discretization (8-meter) is implemented for both models; [[BR]] |
| | 203 | (2) In the current ORC, the soil thermal conductivity and soil heat capacity are not changing with soil textures. In the revised one, the soil texture effects are included; [[BR]] |
| | 204 | (3) the soil heat convection (by liquid water transport) is neglected in current ORC. The soil heat convection and conduction are coupled in the revised ORC.[[BR]] |
| | 205 | ''Models'': [[BR]] |
| | 206 | The LMDZ5B and ORCHIDEE trunk are used. The time step is 7.5 mns, but the radiation is called at each 1 hour time step.[[BR]] |
| | 207 | ''Experiments'': [[BR]] |
| | 208 | Several tests were done in the LMDZOR model (5-day simulation). [[BR]] |
| | 209 | (1) CTL: simulation by using the standard ORC. [[BR]] |
| | 210 | (2) EXP1: same as CTL, but with the revised soil thermodynamics (three modifications introduced in 'background'); [[BR]] |
| | 211 | (3) EXP2: same as EXP1, but soil heat convection is not included (to check if the oscillation is from the numerical solution of soil heat convection).[[BR]] |
| | 212 | (4) EXP3: same as CTL, but radiation is called at every 7.5min (same as physics); [[BR]] |
| | 213 | (5) EXP4: same as EXP3, but revised soil thermodynamics; [[BR]] |
| | 214 | ''Results'':[[BR]] |
| | 215 | Two points under different climate conditions are selected: one point at (25E,0N), humid; another point at Sahara (25E,15N), arid.[[BR]] |
| | 216 | Please see Figs. 1-6 in document: [https://forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Meetings/CMIP6/Physic/test_oscillations_orc_revised_thermo_general.pdf],[[BR]] and Figs. 7-10 in document [https://forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Meetings/CMIP6/Physic/test_oscillations_orc_revised_thermo_radia_step.pdf][[BR]] |
| | 217 | (1) Oscillations are found in humid points (Figs. 1-2) especially when the radiation is called, but not over arid regions (Figs. 4-5). The figures are plotted with 7.5 mn time step.[[BR]] |
| | 218 | (2) The temperature vertical profiles are fine (Figs. 3 and 6) at both points.[[BR]] |
| | 219 | (3) By calling the radiation at each 7.5mn step, the oscillations are NOT removed over humid regions (Figs. 7-8), but they are disappeared over arid regions (Figs.9-10) |
| | 220 | |
