The Impact of Climate Warming on Lake Surface Heat Exchange and Ice Phenology of Different Types of Lakes on the Tibetan Plateau
Round 1
Reviewer 1 Report
This paper addresses a topic that is an important addition to the literature: the responses of lake surface heat exchange and ice phenology as it relates to climate warming - specifically on the Tibetan Plateau which is undergoing rapid surface temperature warming. The paper only compares two lakes. As noted, more model simulations for other lakes on the TP will be crucial for validating this model further. A concern is using sea ice albedo parameterization given that these are freshwater lakes.
The figures (particularly Figure 1) can be cleaned up a bit to make them more readable and appealing to the eye.
Good use of in-situ data (AWS on-site) and remotely sensed data from MODIS. However, the footprint of MODIS is quite large at 500 meters. The lakes are large enough that multiple MODIS footprints can fit, but this should be acknowledged.
Author Response
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Author Response.pdf
Reviewer 2 Report
Review of The impact of climate warming on lake surface heat exchange and ice phenology of different types of lakes on the Tibetan Plateau
Comments to the Author:
This manuscript reports the results of applying a lake model to examine the warming of lake water temperature and the effects on ice phenology. Though the paper is well-written in some parts technically, still it needs to be rewritten following the comments/questions. The interesting part is that two different data sets (in-situ measurement and MODIS observations) are used in the model parametrization/model validation and the experimental set up. In addition to that, there is almost no snow on lake surfaces on the TP in winter!. The author need to show a schematic diagram representing the inputs/outputs and the sensitivity test approach.
More specific comments:
In the Introduction, the effects of factors affecting the lake surface temperature at the air-water interface is not discussed in detail and not referenced.
The use of potential models and their modelling efforts in evaluating the heat exchange and the lake surface temperature is not at all discussed. Why the author preferred this FLake model to apply for this lakes. What are the potentials of this model in estimating the lake temperature and lake ice dynamics in comparison to other lake models?
Furthermore, there are myriads of articles in lake models published in predicting winter lake ice conditions and choosing a best model and applying to this study area will be more relevant and useful for the global scientific community. The author can refer the article: Yao et al. 2014. Comparing ice and temperature simulations by four dynamic lake models in Harp Lake: past performance and future predictions
In the study area, the minimum and maximum air temperature need to be mentioned as the author is doing the sensitivity analysis for air temperature
Section 2.2.1: What is EC Observation system?
In the 5th Paragraph: What are the relevant corrections are included and referred in the article (45). This is not clear. Wind direction and wind speed has major impact on ice-out and ice thickness. How the author discards the turbulent heat flux data over the lake?
The authors should clearly state the major information gap when a significant part of the discussion is referred in an article. However, the author mentioned to refer that significant part in that article in the reference section.
For example: Details can be found in the references [40,41]. What details???? The author need to write in detail. See just above the section 2.2.2
Section 2.2.2: The information in this product is detailed in [46]. What information?
2nd Paragraph: The information in this product is detailed in [48].What information?
Section 2.3.1:
Need to be written in the beginning of the paragraph: 2.3.1. FLake Model:
The FLake model is a freshwater model, and is suggested to be appropriate for lakes with depths of less than 50 m because of its relatively simple stratification scheme. The model requires a small number of lake parameters to be specified: the lake depth and the optical characteristics of the lake.
Section 2.3.3:
The author conducted a series of sensitivity analysis by increasing the air temperature to investigate the lake water temperature and the lake ice. When the model is driven by the inputs variables: surface air temperature, relative humidity, wind speed, air pressure, downward shortwave and longwave radiation, and precipitation from 1 July 2011 to 1 January 2017, what happens to the effect of wind speed and precipitation in the model. When the air temperature is increased from 1.5 deg C to 3.5 deg C, in each simulations, do you believe there is no change in wind speed and precipitation over the lake surface in the atmosphere, which physically doesn’t seem right. Author need to explain the detailed approach of sensitivity analysis and the model forcing scenarios. Need to understand the reality and the practicality of the physical changes and the changes in the model equations to balance the heat budget and the effects of increasing the air temperature.
Section 3.1:
Is the Flake model previously applied to any other environment for similar kind of sensitivity analysis and also for ice phenology study? Need to mention in detail the new insights in this study.
Figure 3. The date is in which format (YYYY/MM/DD?)
Is the model parametrization same for both lakes? Is there any earlier modelling study being done for these lakes? If so, what are those models? How those results are different from the recent Flake model study? Good to show the actual and the adjusted model parameters in a table.
Page 9: In Figure 5, the simulated lake-ice phenology is shown to agree well with the
in-situ observations reported in other studies. Need a reference
Page 10-11: Figure 5: It’s good to show same period of the Observed ice thickness for both lakes. Only 2015 and 2016 winter period is used in this study? This is bit older data and why not the author use the recent data of ice thickness for comparison.
It’s also well understood that model is calibrated only for the winter period. What happens to the thermal dynamics during the transition time: Fall to winter and winter to spring. I feel this is lacking here and need to describe the complete scenario of climate warming and its impact of ice loss.
Page 11: Section 3.2:
2nd Paragraph:
Despite being a significant feature of climate change, and a cause for some
concern, no studies have focused on the impact of rising air temperatures on plateau lakes. What are those concerns????
What is the most significant forcing variable that is impacted from this study for this two morphometrically different lakes? (Based on Fig.6)
Extract from Fig.7&8, the relationships between the mixed layer depth temperatures with ice thickness???
Page 14:
Section 3.2.2 Rewrite the sentence:
As expected, the LST rises with increasing air temperature. And when the air temperature………..
Good to represent the ice phenology metrics in a table format.
Last few lines in the last paragraph: The author summarized differences in the ice phenology metrics for both lakes. Good to describe the reason of these differences for these two morphometrically different lakes. (Refer Fig. 9 & 10)
Page 18:
1st paragraph: Although the model cannot accurately simulate LST
at Lake Ngoring. What’s the reason for this? I guess the model is calibrated only for the winter period? As this paper describes the sensitivity of air temperature and the warming of the lake water temperature, it is essential to calibrate the model for the whole year and not for only winter time. Otherwise, I would suggest try with other models as described in the paper (Yao et al. 2014. Comparing ice and temperature simulations by four dynamic lake models in Harp Lake: past performance and future predictions or see some recent literatures).
Section 4. Discussion and Conclusions:
Make this section as only “Conclusions”.
There are lots of repetitions of the results that has already been discussed in earlier sections. The conclusions section need to be couple of small paragraphs.
Though the author has investigated the sensitivity of air temperature only, Still then the author need to cross check the effect of wind speed and precipitation on ice-on and ice-off. The reason of changes behind the ice phenology metrics are not broadly and clearly described in the manuscript. Check some of the recent publications of Duguay et al that can benefit the authors.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
That is rather interesting study. The most intriguing is the faster increase of temperature during winters. I wish you'll find the solution of the problem.
Author Response
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Author Response File: Author Response.pdf
