# 江南地区近31a的大气环流分型及与温度场演变的关系Classification Characteristics and Application Analysis of Synoptic Flow Patterns during 1987-2017 over the Jiangnan Region

Abstract: In this thesis, by using the Lamb-Jenkinson atmospheric circulation classification method, the daily average sea level pressure data of 1987-2017 years are used to calculate the 6 circulation indices and analyzed the frequency and variation characteristics of different circulation types in different seasons in Jiangnan region. According to the statistical analysis of the 27 types of daily circulation, the major circulation types in the south of the Jiangnan region are E, N and AE, with the frequency of 33.15%, 22.62% and 13.61% respectively. The dominant circulations of the Jiangnan region in spring are N and AN types; the types of dominant circulation in summer are more complex, and the dominant circulation is N, CN, SE, and C types; the dominant circulations in autumn and winter are E-type and N-type, but the frequency of AN-type circulation in winter is higher than E and N types. According to the analysis of the changing rule between the dominant circulation type and the temperature in the south of the Yangtze River, under the control of the AN type, the Jiangnan region is mostly cold weather, and under the control of the CN type circulation in the summer, the temperature in the Jiangnan region is higher.

1. 引言

2. 资料和方法

2.1. 资料

2.2. 方法

$\begin{array}{l}u=0.5\left[P\left(12\right)+P\left(13\right)-P\left(4\right)-P\left(5\right)\right]\\ v=\frac{1}{\mathrm{cos}\alpha }×\frac{1}{4}\left(P\left(5\right)+2P\left(9\right)+P\left(13\right)-P\left(4\right)-2P\left(8\right)-P\left(12\right)\right)\\ V=\sqrt{{u}^{2}+{v}^{2}}\\ {\xi }_{u}=-\frac{\partial u}{\partial y}=\frac{\mathrm{sin}\alpha }{\mathrm{sin}{\alpha }_{1}}×\frac{1}{2}\left[P\left(15\right)+P\left(16\right)-P\left(8\right)-P\left(9\right)\right]-\frac{\mathrm{sin}\alpha }{\mathrm{sin}{\alpha }_{2}}\\ \text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}×\frac{1}{2}\left[P\left(8\right)+P\left(9\right)-P\left(1\right)-P\left(2\right)\right]\\ {\xi }_{v}=\frac{\partial v}{\partial x}=\frac{1}{2{\mathrm{cos}}^{2}\alpha }×\frac{1}{4}\left[P\left(6\right)+2P\left(10\right)+P\left(14\right)-P\left(5\right)-2P\left(9\right)\\ \text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}-P\left(13\right)+P\left(3\right)+2P\left(7\right)+P\left(11\right)-P\left(4\right)-2P\left(8\right)-P\left(12\right)\right]\\ \xi ={\xi }_{u}+{\xi }_{v}\end{array}$

$\left\{\begin{array}{l}v<0,\alpha =\mathrm{arctan}\left(u/v\right)\hfill \\ v>0,\alpha =\mathrm{arctan}\left(u/v\right)+180\hfill \end{array}$

Figure 1. Selected 16 grid points for circulation type classification

 时，为平直气流型(N, NE, E, SE, S, SW, W, NW)；当 $|\xi |\ge \text{2}V$ 时，为旋转型(气旋性A或反气旋性C)；当 $V<|\xi |<2V$ 时，为混合型(平直气流型和混合型的结合)；当 $V<6$ 并且 $|\xi |<6$ 时，则为无定义型 [1] 。这样，可以得到27种不同的环流类型，如表1

3. 环流类型频率特征

4. 环流类型的变化特征

4.1. 环流类型的逐月变化

Table 1. Lamb-Jenkinson circulation type classification scheme

Table 2. Frequency distribution of circulation type during 1987-2017 over the Jiangnan Region

4.2. 主要环流频率的季节变化

Figure 2. Frequencies distribution of circulation types during 1987-2017 over the Jiangnan Region

Figure 3. Variations of the annual frequencies of circulation types N, E, AN, SE and CN during 1987-2017 over the Jiangnan Region

1987~2017年江南地区各季节主导环流出现频率的逐年变化如图4所示。春季主导类型为AN型与N型(图5(a))，1987~2017年春季AN型环流频率平均值为22.0%，N型为42.6%；1988年AN型频率最高(36.7%)，频率最低值(6.7%)出现在2002年，1990年N型频率最高(52.8%)，频率最低值(28.1%)出现在2011年；AN型与N型环流频率之间为负相关。AN型环流的年际变化大于N型。

Figure 4. Seasonal variation of the frequency distribution for 5 major types during 1987-2017 over the Jiangnan Region

Figure 5. Yearly frequency of dominant circulation types for each season ((a) spring, (b) summer, (c) autumn and (d) winter)

4.3. 主要环流频率的年代际变化

4.4. 环流因子地转风V的变化特征

5. 主要环流型与气温的关系

Figure 6. Frequency changes of dominant circulation types during 1987-2017

Figure 7. The changing characteristics of the Geostrophic Wind during January to December

Figure 8. Sea level pressure anomalies of major circulation types during 1987-2017 over the Jiangnan Region

Figure 9. Mean air temperature patterns of major circulation types during 1987-2017 over the Jiangnan Region

Figure 10. The changing characteristics of the mean air temperature of major circulation types during 1987-2017

Figure 11. Mean sea level pressure patterns of dominant circulation types over the Jiangnan Region

6. 结论

1) 用Lamb法划分的环流类型尽管有27种之多，但是绝大多数环流类型出现频率低于3%，NW、NE、CSE、C、CSW、CW、CNW、AN、ANE、ASE、AS、ASW、AW、ANW、UD等15种环流类型从未出现过，S、SW、W、A出现频率较小，C型只是偶尔出现，N、E、CN、SE、AN这5种类型出现频率较高。

2) 各种环流类型的月际变化也各不相同，在1~12月中，E型、N型和SE型常年出现，在10~11月，E型出现的频率已超过15%。C型环流和CN型环流主要出现在夏季，AN型环流类型在冬季频率最高，AN型与C型、CN型呈反相关变化。

3) 对于环流因子地转风而言，在4、5、6月份(春末夏初)，环流因子V的年际变化较小，与平均值相差很小，整体趋势比较稳定。在1、2、3、8、9、10、11月份，地转风V的年际变化较大，但多年来增强或减弱不明显，在各月平均值附近振荡。

4) 春季受E型与N型环流控制，江南地区受北方冷空气影响较大，季平均气温在12~18摄氏度之间；夏季江南地区主要环流型复杂多变，表现为C、SE、CN、N型交替控制，平均季气温在20摄氏度以上，天气变化较大；秋季主要受E型、CN型等环流控制，季平均气温在12~18摄氏度之间；江南地区冬季在AN型环流控制下，江南地区多位低温、晴好天气。

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