the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 19 Dec 2024
Coupling the TKE-ACM2 Planetary Boundary Layer Scheme with the Building Effect Parameterization Model
Abstract. Understanding and modeling the turbulent transport of surface layer fluxes plays a critical role in a numerical weather forecasting model. The presence of heterogeneous surface obstacles (buildings) that have dimensions comparable to the model vertical resolution requires further complexity and design in the planetary boundary layer (PBL) scheme. In this study, we develop the numerical method to couple one of the recently validated PBL schemes, TKE-ACM2, with the multi-layer Building Effect Parameterization (BEP) model in WRF. Subsequently, the performance of TKE-ACM2+BEP has been examined under idealized convective atmospheric conditions with a simplified building layout. Furthermore, its reproducibility is benchmarked with one of the state-of-the-art large-eddy simulation models, PALM, which can explicitly resolve the building aerodynamics. The result indicates that TKE-ACM2+BEP outperforms the other operational PBL scheme (Boulac) coupled with BEP by reducing the bias in both the potential temperature (θ) and wind speed (u). Following this, real case simulations are conducted for a highly urbanized domain, i.e., the Pearl River Delta (PRD) region in China. The high-resolution wind speed LiDAR observations suggest that TKE-ACM2+BEP can mitigate the overestimation in the lower part of the boundary layer compared to the Bulk method at a LiDAR site located in a densely built environment. In addition, the surface temperature and relative humidity can be improved in TKE-ACM2+BEP at surface stations in urbanized areas compared to TKE-ACM2 without BEP. However, it is revealed that BEP may not always imply a better reproduction of surface wind speed as it could exert excessive aerodynamic drag.
- Preprint
(31630 KB) - Metadata XML
-
Supplement
(43709 KB) - BibTeX
- EndNote
Status: final response (author comments only)
-
RC1: 'Comment on gmd-2024-205', Anonymous Referee #1, 12 Jan 2025
Interactive reviewer comment on the manuscriptCoupling the TKE-ACM2 Planetary Boundary Layer Scheme with the Building Effect Parameterization Model
GMD-2024-205
By Zhang et al.
General considerations
In this contribution the authors present the coupling approach of an urban ‘building effect parameterization’ (i.e., the surface exchange parameterization) to a recently proposed (improved) boundary layer parameterization scheme for atmospheric RANS type models. The new coupled scheme is compared to a version with a bulk surface exchange treatment, and to the results from another PBL parameterization (one of the ‘standard schemes in the literature), once with the bulk surface exchange and once with the ‘building effect parameterization’. The approach is evaluated on two case study scenarios with an idealized surface characterization (regular cubes) and an LES (PALM-4U) as a reference. Then, a month-long simulation for the Pearl River Delta (China) with a number of mega-cities (including Hong-Kong) is performed. Data from three lidars (wind profiles), and 31 surface stations (urban and rural) are used for validation.
The study is well designed, and pretty well described (the ‘plan’ for the paper is good, and much of what needs to be known, can be found somewhere). I cannot say, however, that it is well written (I have added quite a number of ‘detailed comments’ – mostly related to language or formulations, etc.). A serious language/style update by a native speaker would certainly greatly improve the value of the paper.
Even if I have labelled one of the comments as ‘major’, I think its resolution is straight forward – so that I can recommend the paper to be published subject to minor modifications.
Major comments
- Real case simulations & data: the presentation of the data is not complete. The lidars, when introduced should be characterized (urban, rural) and some basic information on vertical resolution and accuracy should be provided. Also, for the surface stations, information should be provided on the explicit meaning of the different LCZ classes (‘compact high rise, LCZ1, etc.), and how many are available for each type (how many urban, how many non-urban), what ‘G class’ (e.g., Fig. 17, 18, ..) means. Much of this can be found somewhere (I can, for example add the different numbers in each panel in Fig. 17) but the authors could support the reader in providing this information. Furthermore, Figs. 14-16 have 10 urban classes, plus ‘water cells’ plus ‘natural cells’, while Figs. 17-19 have 7 urban classes (the remaining three are probably not available) plus ‘G stations’ and ‘rural stations’: how do the latter translate to the water cells and natural cells? I suggest to add a sub-section in Section 2 with some of this information.
Minor comments
l.48 ‘…they work with few…’: maybe better ‘they have only been coupled to a few … (I think they would also work with all the other schemes – btu it has not been done)
l.60 ‘have shown that the TKE-ACM2….’
l.62 ‘at the urban station….’: this suggests that the reader knows which urban station is meant. Please rephrase.
l.72 ‘…from the high-resolution lidar’: same as before (this suggests that the lidar had been introduced before). Reformulate to ‘….from a high-resolution lidar’.
l.87 Energy conserving
l.84 ‘…K is the eddy viscosity….’. Do I have to assume that K is equal for all ‘zeta’ (l. 91). If not (what would be better supported by the literature) , K should also get an index zeta.
l.115 ’C_eps is an empirical constant and l_eps corresponds to….’
l.162 uniformly distributed in the vertical: this may be a good idea in a CBL but how about the near surface?
l.164 ‘…one corresponding to a moderately…’
Fig. 2, caption: the different types of lidars should be referenced (UTSS, HT, KP), and briefly explained (possibly in the text) what their strengths weaknesses are.
l.215 ‘…it is found that quasi-….’
l.215 ‘….when LES…’: how is the time for having reached quasi-equilibrium diagnosed?
l.223 usually called ‘turbulent fluxes’. However, it would be better to delete ‘outputted’ - these are just the ‘turbulent fluxes from PALM‘.
l.224 very often, what we can see in a figure has been plotted… (so, the verb ‘to plot’ is somewhat obsolete in this context). May be ‘….schemes are contrasted in …’.
Fig. 6, caption: please add for which case this RMSE is determined and what ‘the truth’ is (assumed to be). Fig. 6: I would find it ‘more convincing’ if the black dots would be displayed as a ‘dotted line’ (and not as a dot at each level) – then it would not appear as a black line in the lower parts of the panels……
- 231 ‘a smaller warm bias’ would possibly sound better
l..234 ‘becomes stable….’: this is indeed a feature of the CBL. Some authors have even defined a ‘neutral level’, i.e. the height where slightly unstable transits into slightly stable (formally, there might even be such a height in the LES)
l.241 ‘….within [the] UCL and near [the ]PBL height where the relatively constant w′θ′ in the middle UCL is not exhibited [reproduced?] in either BEP simulation.’. Here, I think this is a little ’underselling’ the BEP simulations. They at least to some degree reproduce a strong deviation in the profile at canopy height (the two others cannot reproduce this), the relax in the middle of the CBL (and yes, the vertical gradient is too small)…..
l. 249 ‘This has shown the wind shear at the roof level is underestimated…’: I am not sure what the authors want to say with this. Maybe this is just a matter of wording? – ‘thus it appears that the BEP parameterization results in an underestimation of wind shear at roof level, when compared to the LES’.
l. 250 ‘it is discovered…’: first of all I suggest to start a new paragraph. Second, momentum flux decreases (increases in magnitude…) with height. Third, ‘at some height’ (as it appears in the LES) seems to be some 2-4 canopy heights (in b) and d), respectively). Fourth, this cannot be called ‘discovered’ here – this was even one of the reasons for the development of the BEP scheme (i.e., that it had been discovered earlier, that momentum flux was not constant with height in urban canopies).
l.260 ‘similar behavior of the two schemes is found…’
l.275 I think the dashed line is blue in Fig. 5d
l.279 top of the RSL, rather
Fig 7 I suggest to repeat the definition of delta_U (i.e., BEP-Bulk) in the caption. Same in Fig. 8 for theta
l.300 beginning a new sentence: Figure 8…..
Fig. 9, caption: delete ‘plots the’ ; ‘at USTSS, HT and KP’: are these locations? I recall too have seen different symbols in Fig. 2 – and thought this to be different types of instruments. I suggest to add an ultra-short sub-section in Section 2, describing the instrument type, vertical resolution and some accuracy statements from the manufacturer.
l.306 …the rural lidar station HT (first, I learn now that the different symbols are different sites (see previous comment), but also I learn that at least one of the lidars is ‘rural’. Why not giving them an extension in the acronym?
l.306 at the LCZ 5 USTSS lidar location: wouldn't it be perfect to add this LCZ information to the section suggested in ‘comment to Fig. 9’?
l.308 ‘has been reduced’: the authors probably mean ‘is smaller in the BEP schemes….’
l.309 I don’t think there is a Fig. A51… Can the authors adjust?
l.312 starting at an altitude of 50 m agl?
Fig.10/11/12, captions: are these instantaneous values at the given times or 1-hour averages (in both, the observations and the simulation? Also, the caption may remind the reader that the panels start at 8 pm (why is this so?)
Fig. 13: RMSE and mean bias of WHAT? What is the data base? What are the ‘error bars’ referring to?
l.330 convective thermals
l.331 the smallest RMSE and the smallest negative bias….
l.332 Boulac+BEP, which increased the deviations with respect to the Boulac+bulk simulations.
l.334 I cannot locate Section 44.1. please adjust.
l.337 this is not predictability, rather ‘accuracy’
l.342 who is collaborating here with whom?
l.359 as small as…
l.359 ‘…is more likely to be found at around 06LT in TKE-ACM2….’: I don’t think this can be said like that. Do the authors want to say that ‘delta_U10 starts to be larger (in absolute terms) starting from about 06 LT’?
l.366 slightly altered?
l.369 the ‘supplementary Zhang (2024) is not a proper citation (in the supplementary material to Zhang….)
l.377 LC1…stations are …lower than the observed values’: this is, first of all, not a correct sentence (the simulated wind speed at these stations is smaller than…). Second this is a very important observation, which suggests that the authors should (maybe in the appendix) produce a table where the LCZ codes are described in words (having read the sentence, I, for example would wonder what LCZ2 is (it is also having much lower wind speeds than observed….). I suggest to add this finding explicitly to the conclusions (in the present form it states that LCZ1,4, 10 etc. are underestimating – but it is more relevant to state that high-rise and heavy industry types are underestimating.
l.383 ‘at the hill whose…..’: replace by ‘at a hill with a spatial scale of 50 m’.
l.388 ‘Coinciding with Fig. 15’? Maybe: ‘As can be seen in Fig. 15, T2….’?
l.391 ‘their predictability’: it is accuracy and not predictability
Figs17-19: what are ‘G’ stations?
l.400 again, it is not the predictability that is improved, but the prediction (i.e., its accuracy). Predictability is a property of the atmosphere (which is assessed using ensemble prediction approaches)
l.401 should read: ….BEP produces larger RH2 when ….
l.409 building-resolving
Figure 20, caption: Please add the information (in the caption) where the number of sites contributing to a LCZ type can be found.
l.419 BEP suggests that the buildings act..
l.421 …observations are used to…
l.425 …LIDAR station, compared to..
l.430 no predictability
Citation: https://doi.org/10.5194/gmd-2024-205-RC1 -
RC2: 'Comment on gmd-2024-205', Anonymous Referee #2, 07 Feb 2025
Zhang et al., 2025: Coupling the TKE-ACM2 Planetary Boundary Layer Scheme with the Building Effect Parameterization Model
The authors present in the manuscript a development and performance of coupling of TKE-ACM2 PBL scheme with BEP urban model in WRF mesoscale model. Although it describes important and interesting topic of improving of WRF model performance, and also the design of the study seems reasonably, the manuscript is not well written. Sometimes it is hardly readable, confused, some parts are too long but other information are missing. The manuscript have to be substantially improved (or re-submitted) before publishing in GMD.
Specific major comments:
1/ The text of the manuscript is not well transparent, some results parts are too long, model formulation could be also shorter or moved into the appendix. Some short sections (e.g. 2.4) could be removed and the number of figures reduced. Further, the manuscript is hardly readable due to often quick switching between ideas and also missing links to figures. It seems that it was not preciously revised by authors before submission.
2/ Language level is not sufficient, proofreading by English native speaker would be appropriate.
3/ Description of model setting is insufficient, BEP parametrization setting of urban canopy parameters in specific LCZ is missing. Author does not consider possible inaccuracy in the setting of such parameters with impact to model performances in specific LCZ.
4/ Description of LIDAR and station data is incomplete. Some special section about observation data is usual in papers, with information about measuring sites, variables, locations and other important characteristics in view of comparison with model data.
5/ Arrangement of Fig. 7, 8, 14, 15 and 16 shows rather impact of BEP urban scheme compared to Bulk, what is clear and well known fact, but not the impact of TKE-ACM2 PBL scheme compared to Boulac, which is the topic of the paper. Differences between simulations with/without TKE-ACM2 scheme should be rather displayed and also impact of TKE-ACM2 scheme more discussed.
6/ High number of mistakes, typos, wrong use of dashes and connectors (see below). I would recommend to authors to use latex with active references for all figures, sections and tables, to enable better orientation in the text (showing of references by click on) and to prevent mistakes in numbering of figures, sections and tables.
Other comments and technical corrections:
L 12 – comparison to Bulk method, similarly L 27, that’s not clear if Bulk is meant as some simple PBL scheme or simple urban scheme
L 19 – brace near brace doesn’t look well (L 32)
L 23 – 10-50
L 35 – mathematical formula as Fi is superfluous in introduction (similarly L 41)
L 44 – what is urban heat island circulation? UHI or circulation in urban areas.
L 48 – braces in braces doesn’t look well (L 63 similarly, L 154)
L 49 – word order … added recently by H…
L 51 – motivation better explained
L 160 – the horizontal resolution of WRF+BEP in idealized case is not clear
L 175 – WRF+BEP other setting is not described
Chap. 2.4 – why is it separated? Is is used in idealized case, or is it belonging rather to real case?
L 186 – you talk firstly about 10 LCZ and here about 17 classes
L 198 – the formulation “July 18 20 o’clock” is unclear, need reformulate. Similarly the following sentence.
L 204 – this sentence is without any notice about moving to WRF setting
L 205 – Bulk scheme is usually not considered as a canopy model (UCM), because there is no canopy
L 215--220 – acronyms are unclear, all sentences should be written better
Fig. 4 – dotted line is not well visible in plots
Fig. 5 – blue dotted and dashed lines are not in the legend
L 240–250 and further – links to figures are missing, the text is still switching between description of Fig. 4 and 5
L 256 – prorportion → proportion
L 274 – is blue dashed line non-local or local component? (sentence vs. Fig. 5 caption), there is also no red dashed line
L 275–276 – the sentence not clear
L 283 – fount → found
L 283–285 – the sentence is not consistent to claim in L 244. I think a different order of variables in Fig. 4 and 5 vs. Fig. 6 caused it. I would recommend to change the order of variables in Fig. 6
L 289 – what does mean “other natural landuse” – is it any crop, forest or pasture?
L 299 – besides urban grid-boxes, the BEP model is not used over natural and water grid-boxes in simulation, so it cannot produce any direct difference in U, only as an impact of neighbouring grid-boxes
L 302 – the sentence is not correct, there are other mechanisms except anthropogenic heat (e.g. shadowing of solar radiation by buildings), which cause lower temperature in BEP simulation in comparison to Bulk
Fig. 7 – there is no direct comparison of model and observation data
L 309 – there is no Fig. A51 in the manuscript
L 331 – rather “the lowest RMSE and the lowest negative MB”
L 335 – there is no Section 44.1
L 369 – in the supplementary Zhang (2024) → rather in the supplementary material of Zhang (2024) … or similarly
Fig. 17, 18 and 19 – it is not clear, how the stations are assigned to LCZ. Fig. 2 shows only 10 urban stations, but Fig. 17 etc. computes with 23 stations in urban areas.
L 382 – reported in (Ribeiro et al., 2021) – wrong braces
L 400 – “influence of BEP is relatively marginal on RH 2 at non-urban stations” this is quite trivial meaning when BEP is not operating in non-urban grid-boxes.
L 419 – “BEP indicates the buildings act as a sink of heat” – I think this is not a correct statement, there is no sink of energy, the reasons for lower temperature under BEP are different.
Citation: https://doi.org/10.5194/gmd-2024-205-RC2
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 126 | 47 | 8 | 181 | 73 | 7 | 7 |
- HTML: 126
- PDF: 47
- XML: 8
- Total: 181
- Supplement: 73
- BibTeX: 7
- EndNote: 7
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1