|On a strictly factual basis, the authors have responded to my initial comments, and made changes to the paper that address them. It still seems to me that the discussion is fairly clinical, especially for Figures 2-4. I think that there is more information here than what the authors are telling us, that what the reader is provided is more basic reportage than insight into savanna behavior and models’ representation of it. I’m sympathetic to the fact that there is a massive amount of information on these graphs, and not every detail can be described. But it seems to me that there are causal explanations, having to do with model structure and ecosystem behavior, beyond a recitation of which models did what. |
But I appreciate that the authors are showing us model results in Section 3, and then talking about implications and interpretation in the Discussion and conclusions (Sections 4 and 5).
I do still have a few comments and questions about figures 3 and 4:
There is a paragraph about the empirical benchmarks (lines 356-363), but not really in the context of what they show in this figure. There are places where emp2/emp3 perform quite well (dry season LE Howard Spgs), places where none of them seem to have a handle (dry season GPP, Dry River). The authors briefly mention the lack of internal modes and storage capability in emp1-3, but we’re not given much more than that. For example, when emp1 has a peak at a similar value to what is observed, the density is generally much too high. When the peak density is reasonable, there is generally an offset in value. What does this mean? Anything? Does emp1 have value at all other than a low bar for models to clear?
Do the bias vs. flux plots add information beyond what is in the time-course plots? The other reviewer touched on this when asking about the regression lines-do they give us pertinent information or not? There is no discussion about what the bias vs. flux plots mean, beyond what the reader can see for him/herself. CABLE has positive slope at all sites for LE, and crosses zero. To me, this says that during the dry season, at all sites, CABLE underestimates LE. In the wet season, LE is overestimated. But we can see that from the time-course plot. In this case the bias/flux plot seems superfluous: Are there other cases where they are important to the analysis, or can they be discarded?
The positive residuals for BIOS2 at Howard Springs and Adelaide River in Apr-Jun are interesting. That says to me that at these wetter sites, the ‘real world’ dries out quicker than the model does, and water is available for ET in the model. This doesn’t happen in this model at the drier sites. Also, BIOS; Howard/Adelaide are negatively biased in the wet season, more than other sites. With a 10m deep soil for water storage, and 5m root depth for access, I might think that BIOS would do a better job in these wetter sites, but instead the comparison is better in dry sites. Some commentary about some of these types of behaviors in the context of model architecture would be welcome, but I don’t demand it.
The bias vs. flux for LPJGUESS/GPP show a negative slope for all sites but the driest two, which have a positive slope. Does this mean anything, or are these slopes indicating trends that really aren’t there (it appears that the bias at Sturt Plains is always positive). If the latter, is it possible that these regression lines are suggesting facts not in evidence?
If there is actually ‘a larger tendency towards underestimation in the wet than in the dry season’ then we should see a negative bias at larger GPP/LE at all sites. I see this for CABLE;GPP, LPJGUESS;LE/GPP, MAESPA;LE. But I don’t see it for other metrics (CABLE; LE, BESS;LE/GPP, MAESPA; GPP). Am I misinterpreting something?
Typos and errata
Line 100: change ‘savannas’ to ‘savanna’
Line 126: change ‘their ability at simulating’ to ‘their ability to simulate’
Line 143: change ‘savannas’ to ‘savanna’
Line 169: change ‘Table 1, and’ to ‘Table 1, which’
Line 174. Period is on the subscript
Line 212: change ‘simulate water; carbon’ to ‘simulate water and carbon’
Line 220: change ‘BIOS is fine-spatial-resolution’ to ‘BIOS is a fine spatial resolution’
Line 223: change ‘similarities reduces’ to ‘similarities reduce’
Line 223: remove comma after ‘truly’
Line 260: delete ‘then’
Line 261: PALS is given as acronym before it is described in lines 266-267
Line 308: should be ‘Table A1’, not ‘Table B1’
Line 319: delete ‘in the determination of these metrics’
Line 329: add ‘each’ after ‘flux and’
Line 339: delete ‘savanna’. All sites are savanna sites
Line 379: delete ‘vegetation’. Transpiration is from vegetation by definition.
Line 382: delete ‘and’ (first word of line)
Line 457: insert ‘it’ between ‘although’ and ‘performed’
Line 495: should be ‘shrubs are established’ or ‘shrubs have been established’
Lines 530-533: once you say that up to 75% of total LE is from understory herbaceous transpiration, mentioning that C4 understorey will be a large contributor is redundant.
Line 560: change ‘of TBMs’ to ‘of the TBMs’
Line 561: delete ‘that we discuss below’
Line 592: change semi-colon at the end of the line to a comma
Lines 622, 623: change semi-colons to commas
Line 654: delete ‘on’
Line 659. Remove dash before ‘The’