Review of “Effects of spatial resolution on WRF v3.8.1 simulated meteorology over the central Himalaya” by Singh et al.
This manuscript analyzes a high-resolution WRF simulation of the 2011 monsoon season for which there are radiosonde observations from a field campaign (GVAX) for comparison. Three domains are set up at 15, 5, and 1 km, centered at the GVAX site in the central Himalaya. And a fourth domain at 333-m grid spacing is simulated for one month within the longer simulation. With increasing resolution, the WRF domains match the observations increasingly well. But it is only in the 333-m domain that the distribution of winds is at all well represented, due to the inadequate representation of the topography in the coarser domains. This study is novel in (1) the various diagnostics it calculates for its multiple domains; (2) the comparison of model results to an intensive field campaign; (3) downscaling to a 333-m domain and the associated 3s resolution SRTM topography data that resolves individual peaks and valleys. I don’t see any major issues with the manuscript, but I do have a large number of minor suggestions that I would suggest the authors take into account before submitting a revision. In addition, the English language needs to be improved, although the grammatical errors do not detract from the readability of the manuscript. I have detailed all the grammatical errors up to the end of section 2, but thereafter they are too numerous to list. I suggest enlisting a native speaker.
Specific comments
- Including the version of WRF that you used in the manuscript title is perhaps a bit specific.
- L19: anthropogenic pressure → stress from anthropogenic forcing
- L35: “highlighting significance of well-resolved terrain effects” → “, highlighting the importance of well-resolved terrain”
- L51: Spell out GVAX at first use.
- L74: Delete “Of late”. This is redundant in the sentence.
- L88–91: This sentence reads as if High Mountain Asia and the western U.S. are the only places where WRF has been used over complex terrain. I suggest rephrasing to: "WRF has been used for model experiments over complex terrain around the world, e.g., the Himalayan region..."
- L102–104: The last sentence of this paragraph is quite obvious. I would suggest deleting it.
- L105–109: This paragraph is very misleading. You claim that most of the modeling studies over the Himalaya have been at 30–45 km grid spacing, except the Mues et al. study that you cite. But there are in fact many studies that have employed WRF at high resolution over the Himalaya, e.g., Potter et al. 2020 (and references within), Norris et al. 2020 (and references within), and Cannon et al. 2017 (and references within). I think this is an opportunity to better emphasize the novelty of your study. I think your study is novel in (1) the various diagnostics it calculates for its multiple domains; (2) the comparison of model results to an intensive field campaign; (3) downscaling to a 333-m domain and the associated 3s resolution SRTM topography data that resolves individual peaks and valleys. However, this paragraph suggests that the novelty of your study is that it is one of the first to use WRF at 5 km to 1 km grid spacing over the Himalaya, which it is not.
- L107–109: Related to previous comment: “...it remains unclear how the finer resolution could better resolve the complex terrain...”. This sentence suggests an ignorance of all of the previous modeling studies over the Himalaya at convective-permitting grid spacing. Your study is novel in the 333-m domain that you employ (although there may be others that have gone down to this grid spacing over the Himalaya). You should either remove this sentence, or stress here that you are running WRF at sub-kilometer resolution.
- L110–111: Related to previous comments: I suggest deleting: “With this opportunity of model evaluation and improvements in simulating meteorological and dynamical variability over the CH, here”.
- In Fig. 1, the axes in the top panel should be labeled “Longitude” and “Latitude” to match the other panels.
- L171–172: This sentence is redundant and can be deleted.
- L174: You should justify why these dates were chosen, i.e., to match the observation period.
- Section 2.2: You should refer to Fig. 1 for the location of the station, and state its elevation.
- L204–206: This sentence should be in the methodology section.
- L206: “available at 0.75 x 0.75” is repetition of the previous sentence.
- You define the IGP acronym in multiple places. Just need to define it once.
- L225: Delete “and it could be”
- L226: profiles → maps
- L226: “significantly distinct meteorology” is very vague. What do you mean exactly?
- In Fig. 2, I would suggest two or three appropriately chosen elevation contours so that the meteorological features can be related to the topography. Same in Fig. 10.
- L236: distinct → increasingly distinct
- L258: The phrase “overestimated as compared to ERA-Interim” is highly misleading because WRF is probably much more accurate than ERA-Interim. I would suggest rephrasing the sentence to reflect this.
- L258–259: What are the two datasets: WRF and ERA-Interim? This last sentence of the paragraph appears to contradict the preceding text in which you highlight the differences.
- At the beginning of section 3.2, it would help to reiterate the location and elevation of the radiosonde observations (shown in Fig. 1).
- L267: Delete “(c)” (repetition).
- Fig. 3: I would suggest giving the wind speed profiles the same x axis values as other panels, i.e., missing data for the observations up to the beginning of September, so that features in wind can be easily related to features in other variables. Same in Fig. 4.
- Fig. 3: You should clarify in the axis titles of panels g—i that these panels show WRF minus the observations (“difference” is ambiguous).
- L272: The temperature inversion can only be seen on certain days and requires zooming in to see clearly. Maybe regions of negative dT/dp could be marked in the figure?
- L273: 3a → 3d
- L274: this variability → these features
- L279: “wetter (or more humid)” → “more humid”
- L279: dry bias → low-humidity bias
- L288: “normalized standard deviation (SD), normalized to the standard deviation of observation” → “standard deviation, normalized by that of the observations”
- L290: “which turns out to be less than 1” → “, less than 1”
- L293: 50 hPa → 75 hPa (unless the figure legend is wrong?). Related to this point, relative humidity in the stratosphere is not really relevant. It’s probably more appropriate to quote the value at 250 hPa in Fig. 7, i.e., an indication of deep convection.
- L299: Delete “below 500 hPa (Figure 4)” (repetition).
- L303: How can you tell that the model qualitatively captures the vertical profiles if only the differences between the observations and model are plotted?
- L328–330: It is worth mentioning that the higher-resolution models do worse in the upper troposphere for RH? Can you say why this is?
- L348: Figure 6b → Figure 6
- L353: Delete “lower by” (repetition).
- L354: What is Figure 7bs? Do you just mean Figure 7b?
- L358: RH → RH2
- In Table 1, Clarify what the +- sign refers to. And clarify “min/max” - is this the min and max during the full observation period?
- Fig. 6 caption: Explain error bars for observations. Why no error bars for model results? Same in Fig. 9.
- L380: few → a few
- L382: What does 0.35 refer to?
- L396–411: Where are the numbers quoted in this paragraph shown?
- L397: -0.7 → -0.7 g/kg
- L425–443: In this paragraph, you begin stating percentages, e.g., “The dominance of the wind flow over the observational site is easterly (30%)”. Then, you switch to the frequency, e.g., “The frequency of southerly (539) and south-westerly (SW, 481)...” You should pick one, either percentage or frequency, and stick to it to make the text consistent.
- L433: Add “and westerly” after “north easterly”. (The overestimate of westerlies in d03 in Fig.8 should be noted.)
- L435: You quote 27% for south-easterlies in the observations. But earlier you quote 26% (L430). Which is it? The sentence on L434–435 could actually be deleted because it is repetition of a few sentences prior.
- L438: “over predicted by 10%” is misleading. What you mean is “over predicted by 10 percentage points”.
- L439: Insert “in the observations” after “very weak” if I understand correctly?
- L439–441: Where is it shown that the wind direction changed during transitions from high to low wind conditions?
- L450: Why do you quote Figs. 2 and 6 specifically. It seems that this is shown in all figures?
- L452: daughter → nested. Same on L477.
- L458: and the effect→ showing the effect
- Fig. 10: Righthand panel title should be “2m Relative Humidity (%)”
- L478–479: How can you say that the effect of feedback is strikingly observed? Can you be more specific?
- L479: Why “the trend of diurnal variation of the relative humidity”? Don’t you just mean “relative humidity”?
- L489: Delete “(30s or ~0.95km)” (repetition).
- In section 3.5 when you introduce d04, it would be very helpful for the location of d04 to be shown within d03 in Fig. 1 (bottom right panel).
- L502–503: After this sentence it would help to quote the elevation of the station location in d03 versus d04.
- L505: Add “(Figure 11c)” after “d04”.
- L506: “which could be smoothed out if the simulation was carried out with GMTED / or at 1 km with SRTM3s” → “which are smoothed out with GMTED (Figure 11a) or with SRTM3s interpolated to 1 km (Figure 11b)”
- L508–513: Where are all the values that are quoted in these lines shown? Is there a supplementary figure that should be referenced?
- L519: The sentence: “The southerly...model resolution” is confusing. Do you mean ”The frequency of southerlies increases with model resolution, better matching the observations”?
- L522: “while occurrence of south-easterly winds is underestimated” → “with the exception of south-easterly winds”
- Fig. 12. Why are the frequency distributions not shown here, like in Fig. 8? It seems Fig. S5 could be incorporated into Fig. 12?
- L550: pressure → surface pressure
- L557: wind directions → frequency distribution of wind direction
Grammatical errors (up to end of section 2)
- L20: Himalaya → the Himalaya (and in other places)
- L28: the northern → northern
- L32: surface → the surface
- L32: the d01 → d01 (and in other places)
- L33: “and are closer” → “, closer”
- L34: coarser simulation → the output from the coarser domains
- L34: station → the station
- L37: nested domain → the nested domain
- L37: demonstrated → demonstrates
- L42: was → is
- L42: “a frequent southeastward wind component remained underestimated” → “the frequency of southeasterlies remains underestimated”
- L47: Himalayan region → The Himalayan region
- L51: called as → known as
- L55: “hydrological cycle especially monsoon system” →”hydrological cycle, especially the monsoon system”
- L67: terrains → terrain (and in other places)
- L76: Further → Consequently
- L76: have → has
- L77: in past → in the past
- L79: their causes range from mesoscale processes to larger synoptic scale events” → “the associated weather systems range from mesoscale to synoptic-scale phenomena”
- L80: observational network → an observational network
- L82: would → can
- L84: Himalaya → the Himalaya
- L88: “WRF model” → “WRF” or “The WRF model” (and in other places)
- L90: “intermountain west of the United States” → “the multiple mountain ranges in the western United States”
- L100: correctly → accurately
- L101: “Kathmandu valley of Himalaya” → “the Kathmandu valley”
- L102: “attributed to complex topography → “, which they attributed to insufficient resolution of the complex topography,”
- L102: “3 km x 3 km” → “3 km”
- L118: larger Indian region → the larger Indian region
- L122: Subsequent → The subsequent
- L131: prediction → Prediction
- L132: Eulerian → an Eulerian
- L147: “an explicit micrcophysics scheme is needed to resolve cloud and precipitation processes” → “cloud and precipitation processes are resolved by the microphysics (MP) scheme”
- L158: Outer → The outer
- L158: north → the northern
- L159: “Himalayan mountains with vegetation and snow cover” → “and the Himalayan mountains” (why do you need to mention the vegetation and snow cover?)
- L160: “Model atmosphere has 51 vertical levels” → “The model has 51 atmospheric vertical levels”
- L164: “innermost domain 03” → “the innermost domain, d03,”
- L165: mainly to reveal → to resolve
End of review
References
Cannon et al. 2017, Effects of topographic smoothing on the simulation of winter precipitation in High Mountain Asia, JGR Atmos.
Norris et al. 2020, Warming and drying over the central Himalaya caused by an amplification of local mountain circulation, npj Climate and Atmospheric Science
Potter et al. 2020, Dynamical Drivers of the Local Wind Regimen in a Himalayan Valley, JGR Atmos. |
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