《熱帶氣象學(xué)》課件：South_China_Sea_high_2015.4.1

1、2022-3-52022-3-51 1 匯報(bào)人：匯報(bào)人：郭媛媛郭媛媛 導(dǎo)師：導(dǎo)師：溫之平教授溫之平教授 南海高壓的年代際變化特征及南海高壓的年代際變化特征及其與我國(guó)華南降水的聯(lián)系其與我國(guó)華南降水的聯(lián)系2022-3-52022-3-52 2目錄目錄 引言引言 資料與方法資料與方法 南海高壓指數(shù)的定義南海高壓指數(shù)的定義 南海高壓的年代際變化特征南海高壓的年代際變化特征 南海高壓與華南降水的關(guān)系南海高壓與華南降水的關(guān)系 總結(jié)與討論總結(jié)與討論引言引言南海高壓研究進(jìn)展南海高壓研究進(jìn)展3 34 4引言引言南海高壓研究進(jìn)展南海高壓研究進(jìn)展 The South China Sea high (SCSH) ge

2、nerally refers to a closed high pressure system, which appears over the Indo-China Peninsula or the South China Sea (SCS) at the mid-troposphere. The SCSH, a component of subtropical high systems, frequently appears from September to the following April. Comparison with the subtropical high over the

3、 Pacific Ocean shows that the SCSH fluctuates sharply and has a relatively short life cycle. According to the previous studies, the SCSH is closely related with rainfall variability over South China, due to a warm and moist flow located to the northwest of this anticyclone (Liang, 1995).5 5引言引言南海高壓研

4、究進(jìn)展南海高壓研究進(jìn)展 Some efforts have been devoted during the past decades into investigating the variation of the SCSH during the boreal summer (e.g. Wang, 1985; Chen, 1998; Lin, 2000; Wan, 2008). Some researches also pointed out that the SCSH is closely associated with summer rainfall. Although some effor

5、ts have been made to understand the SCSH variation over the tropics in boreal summer, relatively few studies have focused on its variation in wintertime, as well as the relationship with the rainfall over South China.For instance, Wang (1985) defined an intensity index of the SCSH by the point grids

6、 where the 500-hPa geopotential height is greater than 5880gpm over the SCS (100E120E, 10N) 6 6引言引言南海高壓研究進(jìn)展南海高壓研究進(jìn)展 Our focus here is on:Our focus here is on: the definition an appropriate occurrence index, so as to better describe the change of SCSH during wintertime at the mid-tropospheric. the re

7、lationship between the SCSH and wintertime rainfall over South China possible processes responsible for the formation of South China rainfall based on a vertically integrated moisture static energy (MSE) equation7 7資料與方法資料與方法資料出處及方法簡(jiǎn)介資料出處及方法簡(jiǎn)介8 8資料與方法資料與方法資料出處及方法簡(jiǎn)介資料出處及方法簡(jiǎn)介 daily variables derived f

8、rom the National Centers for Environmental PredictionNational Center for Atmospheric Research (NCEPNCAR) reanalysis data from 1948 to 2010 (NCEP-1; Kalnay et al. 1996); daily precipitation data from of 752 weather stations in China from 1959 to 2010, compiled by the Chinese Meteorological Administra

9、tion; Hadley Centre Sea Ice and Sea Surface Temperature datasets (HadISST; Rayner et al., 2003) ; Composite analysis and empirical orthogonal function (EOF) analysis.9 9南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)1010南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù) 南海高壓南海高壓建立標(biāo)準(zhǔn)：建立標(biāo)準(zhǔn)： - -南海區(qū)域范圍內(nèi)應(yīng)有閉合高壓中心：如果區(qū)域內(nèi)南海區(qū)域范圍內(nèi)應(yīng)有閉合高壓

10、中心：如果區(qū)域內(nèi)(107.5(107.5E -E -125125E;10E;10N -22.5N -22.5N)N)某格點(diǎn)的八個(gè)方向上的位勢(shì)高度（即周圍某格點(diǎn)的八個(gè)方向上的位勢(shì)高度（即周圍1616個(gè)格點(diǎn)）均個(gè)格點(diǎn)）均小于該格點(diǎn)，且周圍每個(gè)格點(diǎn)上的渦度小于小于該格點(diǎn)，且周圍每個(gè)格點(diǎn)上的渦度小于 -1-11010-5-5s s-1-1, ,則認(rèn)為在南海存在閉合則認(rèn)為在南海存在閉合高壓?jiǎn)误w；高壓?jiǎn)误w； -南海區(qū)域范圍內(nèi)，南海區(qū)域范圍內(nèi)，700hpa700hpa高度場(chǎng)上的高度場(chǎng)上的3135gpm3135gpm特征線所圍的區(qū)域內(nèi)所有格特征線所圍的區(qū)域內(nèi)所有格點(diǎn)數(shù)相加，其值與南海區(qū)域所有格點(diǎn)數(shù)之比需大于點(diǎn)

11、數(shù)相加，其值與南海區(qū)域所有格點(diǎn)數(shù)之比需大于0.30.3； -在區(qū)域（在區(qū)域（110110E-120E-120E E、1515N-25N-25N N）內(nèi)）內(nèi)v v風(fēng)的區(qū)域平均值需大于風(fēng)的區(qū)域平均值需大于0.0.1111 南海高壓南海高壓面積指數(shù)：面積指數(shù)： - -在在110110E-120E-120E E、1010N-20N-20N N區(qū)域范圍內(nèi)，區(qū)域范圍內(nèi)，700hPa700hPa逐日高度圖上逐日高度圖上3135gpm3135gpm等高等高線所圍的網(wǎng)格點(diǎn)數(shù)之和。線所圍的網(wǎng)格點(diǎn)數(shù)之和。 南海高壓南海高壓強(qiáng)度指數(shù)：強(qiáng)度指數(shù)： - -南海（中南半島）高壓強(qiáng)度指數(shù)：在南海（中南半島）高壓強(qiáng)度指數(shù)：在1

12、10110E-120E-120E E、1010N-20N-20N N（9595E -E -110110E E、1010N-20N-20N N）區(qū)域范圍內(nèi)，）區(qū)域范圍內(nèi)，700hPa700hPa逐日高度圖上將網(wǎng)格點(diǎn)高度值等于逐日高度圖上將網(wǎng)格點(diǎn)高度值等于3135gpm3135gpm的編碼為的編碼為1,3140gpm1,3140gpm的編碼為的編碼為22余此類推累加所得值。余此類推累加所得值。 南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)1212南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)Fig. 1. Spatial pattern of th

13、e mean (a) 700hPa geopotential height (contour, unit: gpm), 850hPa pressure velocity (shaded, unit: Pa/s), (b) vertical integrated water vapor flux (vector) and corresponding convergence (shaded) (c) 850hp and (d)1000hPa horizontal wind for the period 19482010 when the SCSH is occured.1313南海高壓變化特征南海

14、高壓變化特征年代際變化年代際變化& &成因成因14144.14.1南海高壓年代際變化南海高壓年代際變化特征特征1515南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因Fig. 2. The time series of (upper) the SCSH days (red line) and (bottom) the SCSH indices for 19482010. In upper column, the green line represents the days of SCSH when rainfall rate (N) is greater than 10%,

15、while the black one represents that when N is greater than 60%. The definition of rainfall rate (N) is seen in section 4.1. In the bottom column, the red line and the green line denote the SCSHI and SCSA, respectively.1948-1948-197619761977-20101977-2010Average: 32 days1616南海高壓變化特征南海高壓變化特征年代際變化年代際變化

16、& &成因成因Fig. 3. Spatial pattern of the mean 700hPa geopotential height (a) before 1976 and (b) after 1977 when the SCSH is occured. (c) represents the differences between (a) and (b). The shading denotes the differences, being significant at the 95% confidence level.1717南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成

17、因成因Fig. 4. Same as Fig.3, but for the 850hPa pressure velocity.1818南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因Fig. 5. Same as Fig.3, but for the 1000hPa horizontal wind.19194.24.2南海高壓年代際變化南海高壓年代際變化成因成因2020南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因 Q1Q1： 南海高壓強(qiáng)度的年代際變化是什南海高壓強(qiáng)度的年代際變化是什么原因造成的？么原因造成的？ 這種年代際變化是南這種年代際變化是南海高壓自

18、身的變化，還是整個(gè)環(huán)流背海高壓自身的變化，還是整個(gè)環(huán)流背景場(chǎng)的變化？景場(chǎng)的變化？2121南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因Fig. 6. Same as Fig. 3, but the mean states are derived from the whole wintertime (from September to following April).背景場(chǎng)背景場(chǎng)有明顯的年代際增強(qiáng)，有明顯的年代際增強(qiáng)，因此南海高壓的年代際增強(qiáng)因此南海高壓的年代際增強(qiáng)應(yīng)該是對(duì)整個(gè)背景場(chǎng)的響應(yīng)。應(yīng)該是對(duì)整個(gè)背景場(chǎng)的響應(yīng)。2222南海高壓變化特征南海高壓變化特征年代際變化年代際變

19、化& &成因成因Fig. 5. (a) Spatial pattern of the leading EOF mode and (b) corresponding principal component (PC1) of the sea surface temperature (SST) anomalies over the tropical oceans in wintertime for the period 19482010.2323南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因Han et al. 2013Han et al. 2013Fig. 2 Fig. 2 a

20、 a The leading EOF of SST The leading EOF of SST for the Pacific Ocean, based on for the Pacific Ocean, based on 8 year 8 year lowpasslowpass filtered monthly filtered monthly HadiSSTHadiSST from 1900 to 2008, which from 1900 to 2008, which represents the IPO spatial represents the IPO spatial patte

21、rn and explains 35 % pattern and explains 35 % variance. The filtered SST from variance. The filtered SST from 1900 to 2008 is chosen to 1900 to 2008 is chosen to perform the EOF analysis. perform the EOF analysis. b b Same Same as (a) but for the Indian Ocean as (a) but for the Indian Ocean SST lea

22、ding EOF, which explains SST leading EOF, which explains 54 % variance. 54 % variance. c c The leading PC The leading PC (PC1) of 8 year (PC1) of 8 year lowpassedlowpassed SST SST for the Pacific (black curve), for the Pacific (black curve), Indian Ocean (red), and North Indian Ocean (red), and Nort

23、h Pacific (20N; blue). Pacific (20N; blue). d d Variance Variance spectra of IPO index (black spectra of IPO index (black solid curve) and Indian Ocean solid curve) and Indian Ocean SST PC1 (red solid curve), and SST PC1 (red solid curve), and their corresponding 95 % their corresponding 95 % signif

24、icance levels (dashed significance levels (dashed lines).lines).2424南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因圖圖3.2 1976/773.2 1976/77前后冬季前后冬季500hPa500hPa位勢(shì)高度場(chǎng)年代際差位勢(shì)高度場(chǎng)年代際差值值 楚翠姣楚翠姣 2013 20132525南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因圖圖3.3 1976/773.3 1976/77前后冬季前后冬季500hPa500hPa位勢(shì)高度場(chǎng)年代際差位勢(shì)高度場(chǎng)年代際差值值 （7777年后減年后減7777年

25、前），年前），打點(diǎn)地區(qū)為打點(diǎn)地區(qū)為T T檢驗(yàn)通過檢驗(yàn)通過95%95%的的信度檢驗(yàn)區(qū)信度檢驗(yàn)區(qū)全球海溫全球海溫北太平洋北太平洋太平洋太平洋熱帶印度洋熱帶印度洋熱帶西太熱帶西太熱帶太平洋熱帶太平洋熱帶中東熱帶中東熱帶印太熱帶印太楚翠姣楚翠姣 2013 20132626南海高壓與華南降水南海高壓與華南降水聯(lián)系聯(lián)系& &成因成因2727 站點(diǎn)選擇：站點(diǎn)選擇： - -本文所指的華南地區(qū)包括廣東、廣西、海南三省，剔除建站時(shí)間較晚、缺本文所指的華南地區(qū)包括廣東、廣西、海南三省，剔除建站時(shí)間較晚、缺測(cè)時(shí)間較長(zhǎng)、地理位置偏遠(yuǎn)（如西沙站）等站點(diǎn)后共有測(cè)時(shí)間較長(zhǎng)、地理位置偏遠(yuǎn)（如西沙站）等站點(diǎn)后共有5050個(gè)站點(diǎn)的

26、逐日降水資料個(gè)站點(diǎn)的逐日降水資料 。 資料長(zhǎng)度：資料長(zhǎng)度： - -時(shí)間長(zhǎng)度為時(shí)間長(zhǎng)度為19591959 年年1 1 月月1 1 日到日到20112011 年年11 11 月月31 31 日，處理為冬半年后共日，處理為冬半年后共包括包括52 52 年。年。南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)2828 降水率降水率N N： - -式（式（4.2.14.2.1）表征）表征N N 的具體定義，在南海高壓出現(xiàn)當(dāng)天，當(dāng)?shù)木唧w定義，在南海高壓出現(xiàn)當(dāng)天，當(dāng)N10%N10%（即多于（即多于5 5 個(gè)站點(diǎn)有降水記錄），則認(rèn)為該天有降水。個(gè)站點(diǎn)有降水記錄），則認(rèn)為該天有降水。 南海

27、高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)2929南海高壓與華南降水南海高壓與華南降水聯(lián)系聯(lián)系& &成因成因Fig. 2. The time series of (upper) the SCSH days (red line) and (bottom) the SCSH indices for 19482010. In upper column, the green line represents the days of SCSH when rainfall rate (N) is greater than 10%, while the black one repres

28、ents that when N is greater than 60%. The definition of rainfall rate (N) is seen in section 4.1. In the bottom column, the red line and the green line denote the SCSHI and SCSA, respectively.90%51%3030南海高壓變化特征南海高壓變化特征年代際變化年代際變化& &成因成因 Q2Q2： 南海高壓的強(qiáng)度、形態(tài)等因素都南海高壓的強(qiáng)度、形態(tài)等因素都會(huì)引起華南地區(qū)降水的變化，其主導(dǎo)會(huì)引起華南地區(qū)降水的變化，其

29、主導(dǎo)因素是什么？因素是什么？ Q3Q3： 南海高壓形態(tài)特征與華南地區(qū)降南海高壓形態(tài)特征與華南地區(qū)降水范圍的聯(lián)系？其物理過程如何？水范圍的聯(lián)系？其物理過程如何？3131南海高壓與華南降水南海高壓與華南降水聯(lián)系聯(lián)系& &成因成因Fig. 6. Spatial pattern of the rainfall when (a) N60% and (b) N60% and (right) N10%. In upper column, 850hPa pressure velocity is shaded. The shading represents that the wind speed is grea

30、ter than 5 m/s in middle column. In (e) and (f), the shading denotes the corresponding divergence.3333 濕靜力能方程：濕靜力能方程： - - 南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)Cited from: Chou et al. (2009)其中：其中：TqnetphVVF 3434南海高壓與華南降水南海高壓與華南降水聯(lián)系聯(lián)系& &成因成因Fig. 8. Same as Fig. 7, but for the temperature advection, mois

31、ture transportation and the net heat flux into the atmosphere column.3535 濕靜力能方程：濕靜力能方程： - - 南海高壓指數(shù)定義南海高壓指數(shù)定義建立指數(shù)建立指數(shù)& &強(qiáng)度指數(shù)強(qiáng)度指數(shù)In sum, the shape of the SCSH could significantly influence the rainfall extent over South China. the contributions of the temperature and moisture advections to the moist

32、static energy are positive, resulting in extensive rainfall over the South China. TqnetphVVF 3636總結(jié)與討論總結(jié)與討論3737總結(jié)與討論總結(jié)與討論 To examine the occurrence of the SCSH, a new definition of the SCSH days is proposed in the present paper. About 2029 days of SCSH were detected during the 63 winters from 1948 to 2010 based on the new establishment index. It