Long-term eddy modulation inhibited the meridional asymmetry of halocline in the Beaufort Gyre
Abstract. Under the background of wind forcing change along with Arctic sea ice retreat, the mesoscale processes undergoing distinct variation in Beaufort Gyre (BG) region are more and more significant to oceanic transport and energic cascade, and then these changes put oceanic stratification into a new state. Here the varying eddies and eddy kinetic energy (EKE) in the central Canada Basin (CB) and Chukchi–Beaufort continental slope are obtained based on mooring observations (2003–2018), altimetry measurements (1993–2019) and reanalysis data (1980–2021). In this paper, the variability of halocline in BG representing adjustment of stratification in the upper layer is shown so as to analyze how it occurs under significantly changing mesoscale processes. We find that the halocline depth has deepened by ~40 m while that in the north has deepened by ~70 m in the in the last nearly two decades by multiple data sets. The halocline depth lifting to the north initially was shifted to a final nearly symmetric structure. Eddy strength and Eddy induced low salinity water transportations have been continuously increasing toward the central basin at the mean time the halocline depth and strength among the southern and northern parts in the basin have reached a nearly identical and stable regime. It is clearly clarified that the long-term dynamical eddy modulation through eddy fluxes facilitating the freshwater redistribution inhibited the meridional asymmetry of halocline of the BG. Further research into high-resolution observations and data simulations can helps us to better understand the eddy modulation processes and its influence on large-scale circulation.
Jinling Lu et al.
Status: final response (author comments only)
- RC1: 'Comment on egusphere-2023-501', Anonymous Referee #1, 30 Apr 2023
- RC2: 'Comment on egusphere-2023-501', Anonymous Referee #2, 21 May 2023
EC1: 'Comment on egusphere-2023-501', Karen J. Heywood, 22 May 2023
- AC1: 'Reply on EC1', Ling Du, 23 May 2023
Jinling Lu et al.
Jinling Lu et al.
Viewed (geographical distribution)
This paper explores the relationship between the varying eddy field and the changes in the shape and depth of the Beaufort Gyre halocline in the past two decades. The authors used in-situ observations, altimetry, and reanalysis data, to describe the changes in the halocline structure, with an emphasis on the meridional asymmetry. They then examined eddy activities, from both individual eddies and kinetic energy perspectives, and connect them to halocline structure via available potential energy. The study found that eddies played an important role in redistributing fresh water and thus adjusted the halocline structure through analysis of eddy fluxes. Despite the paper’s intriguing ideas, the writing is unclear, making it very difficult to follow. The overall flow needs improvements. Therefore, I cannot recommend this paper to be published in its current form.
Line 132: Could the authors explain how eq (3) relates to this sentence?
Line 146: This is not the right place to insert citation.
Line 205-206: Mooring C ends before 2008. How can we make a conclusion about the shape in the northeast and northwest in recent years?
Figure 3: APE at a single point is not meaningful. It represents the slope of the halocline in a region, not a single point. The reference density in the APE equation is related to some mean density across the field. Authors should make it clear.
Figure 6: The lengths of data available are determined the days of open ocean. Will different data lengths impact the results?
Figure 6: The plot is from satellite data, so I assume it indicates surface EKE. How is it related to the previous paragraphs in which subsurface EKE are discussed?
Line 306: This statement made based on observations from two points. Other factors could be responsible. For example, eddies were generated near the mooring site; or the eddies simply did not pass by the mooring.
Figure 10: How is the probability estimated?
Line 399: Eady timescale is not interpreted previously.
The authors described both surface and subsurface EKE. There could be asymmetry in the surface sea level and subsurface halocline. How does the surface EKE relate to the subsurface halocline shape?
To show how the writing could be improved, I will provide some wording issues in the first 50 lines. Please not that this list is not exhaustive, but rather serves as a guide for improving the paper’s overall clarity.
Line 10: Please specify the “varying eddies”. Number, shape, velocity?
Line 16: This long sentence is confusing. Maybe it would be clearer if breaking into several shorter sentence.
Line 16: The second “Eddy” should not start with capital letter.
Line 30: This sentence is not grammatically correct.
Line 37: It should be “paid attention” instead of “payed attention”
Line 39: “The increase of isopycnal slop with depth” is a new piece of information and it should be introduced before directly describing the mechanism.
Line 42: “Likewise” used here is confusing. The previous and this sentence do not have characteristics in common.
Line 43: Should be “identified as”.
Line 46: high resolution eddy-resolving?
Line 47: “etc” should not be used.
Line 48: “focused on” instead of “focus”.
Line 48: “Moreover” is not correctly used here. The following sentence changes the topic.
Line 50: “even they may extend”?