My goal is to show how to write “better” (mainly in terms of grammar in this case).

目的：提高读者的科技英语写作水平(不是跟作者过不去)。

Green highlight is used to show good writing.

绿色: 好好学习。

Yellow means "questionable."

黄色：有问题。

Blue: Pay attention.

蓝色：需要关注。

Observations and Dynamics of Circulations in the North Indian Ocean

https://link.springer.com/book/10.1007/978-981-19-5864-9

Authors:

·       Julian P. McCreary , 

·       Satish R. Shetye

Blogger’s note: Don’t let the “north” in the book title mislead you. They authors define “North Indian Ocean” clearly, at the beginning, to include the region north of 10ºS.

Part IV 

Forced Solutions 

Chapter 9 Overview 

Abstract This chapter provides an overview of the wind-forced solutions obtained in the rest of the book. It first notes common aspects among all the solutions: the equations solved, boundary and initial conditions imposed, and forcing structures used. Then, it reviews mathematical concepts involved in finding many of the solutions: the Dirac δ-function and its properties, and Fourier and Laplace transforms. To conclude, solution methods used in later chapters are illustrated by solving a simplified version of the LCS equations, one with f = 0 and no meridional wind. Solutions are obtained for both switched-on and periodic winds, using both direct and transform methods. 

Blogger’s note: This sentence should use active voice.

Chapter 10
Ekman Drift and Inertial Oscillations 

Abstract Solutions that illustrate Ekman drift and inertial oscillations are obtained under a variety of settings: for a single mode of the LCS model; as a function of depth z both with and without a surface mixed layer; and for constant and variable f . At midlatitudes, the steady Ekman drift associated with a single mode of the LCS model is oriented to the right (left) of the wind in the northern (southern) hemisphere and, when the modes are summed, the solution converges to the classic Ekman spiral; however, if the Ekman drift is confined to a surface mixed layer as is commonly observed, the spiral structure is lost for sufficiently (realistically) strong vertical mixing. Ekman drift also exists near the equator, remaining finite there because pressure is involved in the dynamical balance. In response to zonal winds, Ekman drift diverges from the equator (equatorial Ekman pumping), generating a zonal jet that continuously accelerates (the Yoshida Jet). Inertial oscillations are generated whenever winds are switched on. When f varies, their energy propagates efficiently away from the latitude where they were generated along ray paths predicted by their dispersion relation, a process known as β-dispersion. 

Blogger’s notes: 

1) No need to use semi-colon. 

2) I prefer “dynamic” whenever possible.

Chapter 11
Sverdrup Flow and Boundary Currents 

Abstract In his original paper, Sverdrup obtained a steady-state solution to the depth-integrated fluid equations without momentum advection and mixing. That fundamental response is now called a “Sverdrup flow” and the balance of terms that generates it a“Sverdrup balance.” A mode of the LCS model can also be in a state of Sverdrup balance,and it is useful to refer to that response as also being a Sverdrup flow. In response to forcing by zonal winds, Sverdrup flow extends west of the forcing region, owing to Rossby-wave radiation. In contrast, when forced by meridional winds Sverdrup flow is confined to the forcing region, because the total Ekman pumping cancels out across the region; however, when there is vertical diffusion, the cancellation isn’t complete, allowing the response to extend west of the region. Sverdrup flows that extend to the western boundary of the basin,are closed by western-boundary currents confined to narrow boundary layers. Solutions are obtained for the well-known, frictional, western-boundary layers obtained by Stommel and Munk. Dynamically similar boundary layers exist on eastern, northern, and southern basin boundaries, and in the interior ocean along edges of forcing regions. 

Blogger’s notes: 

1) Try this: That fundamental response is now called a “Sverdrup flow”; and the balance of terms, which generates the flow, a “Sverdrup balance.”

2) The comma in line 4 should be a semi-colon. 

3) Spell out “isn’t” to be “consistent.” 

4) The comma after “the basin” is a typo. 

5) “On” is not as good as “along.”

Chapter 12 Interior Ocean 

Abstract Wind-forced solutions are found to a simplified version of the LCS equations that neglects the acceleration and damping terms in the zonal and meridional momentum equations. When the wind is switched on, the Coriolis parameter f is constant, and there is no vertical diffusion, Ekman flow continuously drains (piles up) water to the left (right) of the wind axis in the northern hemisphere, and vice versa in the southern hemisphere, a process known as open-ocean Ekman pumping. When the wind is switched on and f varies, Ekman pumping is stopped by the radiation of Rossby waves, and without mixing the response adjusts to a steady-state Sverdrup flow. When the wind is periodic, these processes vary continuously. 

Blogger’s note: Should be “, which neglects…”

Chapter 13 Coastal Ocean 

Abstract Wind-forced solutions along eastern and western coasts are found to a simplified version of the LCS equations that neglects the acceleration and damping terms in the zonal momentum equation. All are forced by a zonally-independent band of meridional wind stress τ y that is either switched-on or periodic. Most are discussed in terms of a one-layer, reduced-gravity model (a 1 21 -layer model) with layer-thickness h. For switched-on winds, solutions are obtained: i) in two dimensions (x, h) when the Coriolis parameter f is constant; and in three dimensions (x, y, h) when (ii) f is constant and (iii) f varies. In case (i) and without vertical mixing, h continuously thins at the coast, a process known as “coastal Ekman pumping.” In case (ii), the thinning is weakened or eliminated by Kelvin-wave radiation, which establishes an alongshore pressure gradient that balances τ y . In case (iii), the coastal response is further modified by Rossby-wave propagation, which: from an eastern coast carries the coastal currents completely offshore; and from a western coast continuously narrows the currents (without viscosity) or adjusts them to a Stommel or Munk layer (with viscosity). These solutions are modified to provide a simple representation of the coastal response forced by river outflow. 

Blogger’s note: Semi-colon should be replaced by a period.

Chapter 14
Equatorial Ocean: Switched-On Forcing 

Abstract Near-equatorial solutions forced by switched-on winds are found to a simplified version of the LCS equations that neglects the acceleration and damping terms in the meridional momentum equation (the “long-wavelength” approximation). They are found under the assumption that the Coriolis parameter is given by 

f = βy, allowing them to be represented as expansions in Hermite functions. In an unbounded ocean, Ekman drift and Ekman pumping quickly establish an accelerating jet, the Yoshida Jet. Subsequently, the radiation of equatorial Rossby and Kelvin waves adjusts the response to a Sverdrup-balanced state plus a zonally-independent, equatorial jet that does not accelerate, the “bounded” Yoshida Jet. With an eastern boundary, the equatorial Kelvin wave reflects as a packet of Rossby waves, which has a characteristic wedge-shaped pattern as it radiates offshore. With both boundaries, signals are present with a period P close to the time it takes an equatorial Kelvin wave to cross the basin and the lowest order ( j = 1) Rossby wave to return; period P is a natural “ringing” time of the basin, and is the basis for equatorial basin resonance discussed in the next chapter. 

Blogger’s note: Semi-colon should be replaced by a period.

Chapter 15
Equatorial Ocean: Periodic Forcing 

Abstract A near-equatorial solution forced by periodic winds is obtained to the complete LCS equations. It is found assuming that the Coriolis parameter is f = βy, allowing it to be represented as an expansion in Hermite functions. The same processes identified in the previous chapter for switched-on winds occur in the periodic one, except that they happen continuously rather then sequentially. When there is an eastern boundary, the wind-forced equatorial Kelvin wave reflects as a packet of Rossby and evanescent waves, with Rossby waves existing only equatorward of the critical latitude θcr , and evanescent ones superposing to form a β-plane Kelvin wave north of θcr . With both boundaries, two types of resonant responses are possible: “equatorial basin resonance,” which is linked to the natural ringing time of the basin; and “zero-group-velocity” resonance that occurs when the ocean is forced at the critical frequency of an Rossby or gravity wave. 

Blogger’s note: Clearly, “then” should be “than.”

[Bloggers’ Note: Chapter 13 covers both switched-on and periodic forcing.]

Chapter 16
Beams and Undercurrents 

Abstract The complete solutions to the LCS model are superpositions of the responses to many modes. In these solutions and for periodic forcing, wave energy propagates both vertically and horizontally along ray paths determined by the wave’s dispersion relation. Provided the ray-path slopes are independent of wavenumbers, the responses have a beam-like structure. Solutions are found that illustrate beams associated with coastal and equatorial Kelvin waves, Yanai waves, and equatorial Rossby waves. For constant background stratification Nb, the beams are very clear, but when Nb varies with depth they are blurred by reflections of wave energy in regions where Nbz ̸= 0. For switched-on forcing and when vertical mixing (damping) is sufficiently large, solutions adjust to steady-state, coastal and equatorial circulations that have realistic undercurrent structures. 

Chapter 17
Cross-Equatorial and Subtropical Cells 

Abstract The Cross Equatorial (CEC) and Subtropical (STC) Cells are the major shallow-overturning cells of the Indian Ocean, corresponding to the North and South STCs in the Pacific and Atlantic Oceans. Their meridional (overturning) structure is illustrated by two-dimensional (y, z) streamfunction plots from two solutions to ocean general circulation models (OGCMs). The plots show that the cells’ sinking branches are located in the southern hemisphere, whereas their upwelling branches are located in the southern hemisphere along the South Equatorial Thermocline Ridge for the STC, and in the northern hemisphere for the CEC. The cells’ three-dimensional (x, y, z) structures are determined by following pathways of model drifters in solutions to two layer models and an OGCM. Transports of the cell branches in each solution are compared to each other and to available observations. A suite of solutions to an idealized two-layer, reduced-gravity model (a 2 21 -layer model) is used to isolate the basic processes (wind forcing, upwelling, and detrainment) that generate the cells. In addition to the CEC and STC, the solutions have an equatorial “roll,” a small-scale overturning feature confined to the upper 50–100 m within a few degrees of the equator; its dynamics are discussed, and observational support for its existence noted. 

Blogger’s note: 

1) Try: The Cross-Equatorial (CEC) and Subtropical (STC) Cells are the major shallow overturning cells of the Indian Ocean, corresponding to the North and South STCs in the Pacific and Atlantic oceans. 

2) Use “two-layer.” 

3) It’s better to replace the last semi-colon with a period. 

4) Most people use “dynamics is discussed.” 

5) Try “is noted.” Or “, noted.”