General comments:

This work provides an interesting and valuable analysis of on- and offshore wind patterns near the northern coast of Japan, making a case for the importance of doing so given the expanding development of offshore wind energy development. The authors make use of a unique (to this region) data set of lidar and sonic anemometer wind data covering a full annual cycle, September 2023-August 2024. They use 10-minute averaged data to investigate the frequency, seasonality, diurnal variation, and direction-dependence of LLJ occurrence, and connect their results primarily to land-sea contrasts and the resulting sea- and land-breezes. Their findings will be of interest to both wind plant developers and operators and to climate researchers.

The authors make some comparisons between LLJs in this area of Japan and LLJs that have been studied in other offshore regions. Despite the authors' description of the uniqueness of this region (lines 48-50), I am a little skeptical about these comparisons given that the authors use a specific definition of an LLJ (Eq. 2) that is not the same as what (apparently) is a more common definition (Eq. 1). I believe it will be helpful for readers - and that it will strengthen the paper - for the authors to provide an explanation of how the identification of LLJs is affected by their choice to use Eq. 2. For example, are you over- or underestimating LLJ occurrence with Eq. 2 vs. Eq. 1? And I am especially curious about how your results (figures 3-6 and table 3) might differ if you used Eq. 1 to identify LLJs rather than Eq. 2. I believe it is important to more fully explain and justify your choice of Eq. 2, given that the rest of the paper relies entirely on this definition.

Specific comments:

(1) Figure 2: This figure is difficult to interpret. How exactly does the figure compare the detection criteria? It seems more like the figure is identifying how umax and umin are identified from the profile, and then LLJ presence is based on Equations 1 and 2 rather than the figure itself.

(2) Line 156: You already have an Equation 2, so the equations starting here need renumbering.

(3) Lines 172-174: "Based on the NEDO Wind Observation Guidelines (2023), wind speeds 120 m above the onshore and offshore areas were compared for 16 wind directions. The classification of wind direction was determined using 120 m wind direction data from the offshore Doppler LiDAR." Does this mean you are using the 10-minute average wind speeds (lines 137-138) to identify LLJs every 10 minutes?

(4) Figure 3: Related to comment (3) above, what do the dots in this figure represent? Does each dot represent one 10-minute detection of a LLJ? 

(5) Line 193: Why are land breeze directions WNW and WSW but sea breeze direction is only E?

(6) Figure 4:

• Did you look at the vertical profiles for all 16 directions for each season? Are these the only ones that show LLJs?
• Is the sample size the number of 10-minute averages from your one-year data set? Is it the number of hours in your one-year data set when LLJs are detected? This is not clear to me.
• Also, I don’t see season labels on this figure, but maybe they’re just small enough that I can’t find them?

(7) Table 3:

• It would be helpful to see this for all 16 directions, as justification for focusing your analysis on these specific directions.
• Is the sample size the number of 10-min wind speeds in your one-year data set? If so, this is a very small N compared to the number of 10-minute periods in a full year.

(8) Lines 233-234: E has a similarly small sample size, so why not the same caveat?

(9) Lines 308-311: I think you are saying your result actually is consistent with Blackadar's theory, given that "the thermal gradient between onshore and offshore areas" is what drives sea breezes?

(10) Line 329-330: "LLJs were frequently observed when winds were parallel to the coastline, particularly during spring and summer..." How frequent? How many hours per year or per season?

(11) Lines 331-332: "Detailed analyses..." What about the LLJs that you associate with N and S directions, which are parallel to the coast and thus not sea breezes? I note that the N and S occurrences are more frequent than E (sea breeze) occurrences, per your table 3.