標題和作者

• 標題：[A Dynamically Constrained Method for Determining the Vortex Centers of Tropical Cyclones Predicted by High-Resolution Models](file:///E:/學習/論文/高原渦位置確定/Xu-2015-JAS----動力學新方法確定中心.pdf)
• 作者： QinXu ---National Severe Storms Laboratory, Norman, Oklahoma
• 預計時間，我也不知道

一、自己的總結、評價和應用

1. 通過動態約束的方法來確定渦旋中心
2. 方程3.1和3.2根據梯度風，通過判斷e的值來確定中心，但是e隨r變化很大，所以還需要用動力條件疊加上去算
3. 用了很多迭代的演算法，對於高原渦系統適用性如何？
4. 主要是滿足梯度風條件和動力條件，根據兩個條件，分別算e的最小值和J的最小值中心，滿足對應的方程，然後一步一步算

二、文章的主要問題（在摘要中找到，變成疑問句）

This paper proposes a new method to properly define and accurately determine the vortex center of a model-predicted tropical cyclone (TC) from a dynamic perspective.

三、結論（摘要和結尾處）

四、思維脈絡（寫下小標題以及各個標題中的關鍵句），用筆畫出關鍵

1. Introduction

1. how to properly define and accurately determine the TC vortex center in model-predicted fields
   remainsunclearintheory
2. This paper aims to address this issue by considering not only the key
   kinematic feature but also the gradient wind balance
3. A dynamic optimality condition for defining the TC vortex center is derived in section 3 after a brief review of the previous schemes insection 2. An innovative method for finding the TC vortex is developed in section 4 using the dynamic optimality condition. The effectiveness of the new method is demonstrated in section 5 followed by conclusions in section 6.

2. Review of previous schemes and the importance of the concerned issue

a. Previous schemes

1. the wind speed centroid in the disturbance field at the top of the boundary layer within a subdomain centered at the grid point nearest to the observed TC center.   最接近觀測的TC中心的網格點區域內邊界層頂擾動場的風速中心
    - the vortex center, yields the highest peak in the radial profile(徑向輪廓）of the azimuthal-mean (徑向平均)tangential wind (切向風)，這個地方的徑向風切變應該也是最大的
    - 這個是完全從運動學上考慮的
   
2. the TC vortex center is determined by using the vorticity maximum at the top of the boundary layer ( $\eta$ = 0.85 , about 850 hPa).
    - the computed vorticity, denoted by $\xi$ , has to be heavily smoothed by applying a (1/4,1/2,1/4)-weighted three-point averaging in the x and y directions alternatively for 50 times.
    - 進行了多次非常強的平滑，真實的渦度中心在它的幾個中心的中間
    
3.  by checking 850-hPa wind directions adjacent to the grid point being checked
    - 這個就是看風向，不過也是完全從運動學的角度去看，且得到的中心時離線的點

4. to search for the vorticity maxima at 10 m and at 850 and 700hPa, the pressure minimum at the mean sea level, and the geopotential height minima at 850 and 700hPa in the continuous space of (x, y) within 225 km of the NHC-observed TC center.
    - 這是個聚合的方法
    - 10m、850hPa、700hPa的渦度最大值；海平面上的氣壓最小值；850和700hPa的最低位勢高度
    - 再研究區域內的10m、850hPa和700hPa的風速
    - 把上面的幾種資料和觀測資料的位置取平均
    - 這種研究是很經驗主義的,沒有動態的限制，使用最大最小值可能會受到小擾動的強烈影響
    
5. 動態的追蹤和精確的定位

b. The concerned issue and its importance

1. 用根據渦旋中心來定的梯度風來確定渦旋的邊界對渦旋中心不敏感

2. ifthe extracted TC vortex is not reused but replaced by a properlyspecified vortex, then the vortex center does not have to be determined very accurately in the continuous space of (x, y) and can be searched merely on the model grid as implemented by the refined scheme of Kurihara et al. (1995). 

3. 也就是說要用一個精確定義的渦旋來代替原來的渦旋

4. If the extracted TC vortex is not only relocated but also adjusted in size and intensity(強度) to match the observed values,那麼就既需要運動學上的平衡，也需要動力學上的平衡

5. the axisymmetric part of the extracted TC vortex should retain the gradient wind balance as much as possible，保持梯度風平衡

6. determine the TC vortex center based on the required dynamic balance in the model-predicted field becomes critical. 基於動力學，來確定模式預報的熱帶渦旋中心

7. 還可以提高預報準確率，反正報準渦旋中心很重要就是了

3. Gradient wind balance and dynamic optimality condition(梯度風平衡和動力平衡的條件)究竟是什麼樣的條件呢

a. Gradient wind balance


梯度風的條件，就是算e的值，e是擾動量，越小越好，

\(r_e = 2r_m\)時，e最小值位置和低渦中心位置最接近，但是包含有很多其他的小值中心
當\(1.5r_m < r_e < 3r_m\)時，e最小值刻畫低渦中心位置還可以，在這個範圍外就不怎麼行了
所以光使用e的值來判斷還不夠

b. Dynamic optimality condition

直接使用渦度的高值中心確定低渦中心並不準確，這裡引入了流函式。

最後推出需要滿足3.5

\(J(x_c,y_c,\omega,\psi_0,\pi_0)\)

4. The new method

a. Tranformation of ocntrol variables

a,b,c,d看成常數，都可以算出來，最後是要算4.3式

b. Computational procedures of the new method

1. $根據(x_{c1},y_{c1}),\omega_1初步推算出x_c,y_c,\omega$，滿足3.4式
2. 滿足3.3式，來確定$(x_{c2},y_{c2}),\omega_2$
3. 同時滿足4.2和4.3式，

5. Effectiveness and computational efficiency of the new method

a. Test with a mature TC
b. Test with a weak tropical storm at the incipient stage

6. Conclusions

五、參考文獻列表