TC Watch / 熱帶氣旋 > Selected TC Review / 重要熱帶氣旋回顧 > 201507W (DOLPHIN 白海豚) [Refresh 更新]
 201507W (DOLPHIN 白海豚) - Profile 檔案 |
(Issued on June 11, 2015)
(於 2015 年 6 月 11 日發出)
Brief profile of DOLPHIN 白海豚小檔案:
| JTWC number 聯合颱風警報中心 (JTWC) 號碼 | 07W |
| International number 國際編號 | 1507 |
| Period of existence 生存時期 (JTWC) | 2015/05/07 02 HKT - 2015/05/20 08 HKT |
| Lifetime 壽命 (JTWC) | 13.25 days 日 |
| Maximum 1-minute wind (JTWC) JTWC 一分鐘平均最高中心風速 | 140 knots 節 (Category 5 Super Typhoon 五級超級颱風) |
| Minimum pressure (JTWC) JTWC 最低氣壓 | 918 hPa 百帕 |
| Highest TC signal by HKO (if applicable) 香港天文台發出最高熱帶氣旋警告信號 |
N/A 不適用 |
| Closest point of approach by HKO (if applicable) 香港天文台所示之最接近距離 (如適用) |
N/A 不適用 |
| Time of closest approach by HKO (if applicable) 香港天文台所示之最接近時間 (如適用) |
N/A 不適用 |
| Lowest pressure recorded at HKO (if applicable) 香港天文台錄得的最低氣壓 (如適用) |
N/A 不適用 |
TC track from HKWW 本站的熱帶氣旋路徑圖:
| Past HKWW Bulletins on DOLPHIN 本站有關白海豚的發佈 |
Please click here for bulletins on DOLPHIN. 請按這裡。
| Storm Summary 氣旋摘要 |
Unless otherwise stated, all times below are in Hong Kong Standard Time (UTC+8)
除非特別註明，下文時間均為香港標準時間 (協調世界時加 8 小時)
Following NOUL earlier in May, DOLPHIN also reached category 5 strength as it crossed northwestern Pacific. A patch of convections persisted south of Pohnpei in early May. It intensified into tropical depression 07W early on May 7. At formation, 07W's convections were restricted to its periphery, and the storm was expected to take some time to consolidate. Despite its loose appearance, a wind field analysis on May 8 depicted a circular, closed circulation with strong force winds near its centre.
Due to the prevalence of low-level westerly wind, 07W moved east to east-southeast on May 7 and 8. The storm was rather large in scale, and failed to intensify much initially. As the westerlies diminished, 07W decelerated and turned north along a small weakness in the subtropical ridge. The JMA upgraded 07W into a tropical storm at 8 pm May 9, naming it DOLPHIN. It was the seventh tropical storm of the year in this basin, and this beat the old record of earliest seventh tropical storm by almost 10 days (Tropical Storm CARLA on May 19, 1971). DOLPHIN was expected to move north along the weakness, before turning west as the ridge would then strengthen.
In the next two days, DOLPHIN slowly tracked north without much intensification. It halted and turned west on May 11 at around 10°N, with its circulation centre still partially exposed. More substantial strengthening occurred on May 12; organized patches of convections finally managed to wrap around DOLPHIN's centre, and the storm became more symmetric. It was upgraded into a severe tropical storm, and further into a typhoon on May 13. DOLPHIN started to take on a west-northwesterly track as it accelerated to around 20 km/h.
A pinhole eye appeared briefly on May 13, but collapsed several hours later. Intrusion of drier air was evident; however DOLPHIN was able to overcome this by tightening its structure and a size reduction. Together with reduced shear, DOLPHIN continued to intensify on May 15 as it passed just north of Guam. Hurricane force winds were recorded on the Island. Shortly after passing Guam, DOLPHIN deepened rapidly by exhibiting a solid, annular eyewall with an embedded eye of around 50 km in width. The JTWC upgraded DOLPHIN into a 130-knot (241 km/h) super typhoon at 2 pm May 16, and then to a 140-knot (259 km/h) category 5 equivalent cyclone 12 hours later. Despite having the same peak intensity as NOUL, DOLPHIN's appearance was apparently inferior; its eyewall cloud-top temperatures were above -70 degrees at times, and its eye was not as clear as NOUL's1. The maximum intensity assessed by the JMA was 100 knots (185 km/h), with an estimated central pressure of 925 hPa.
DOLPHIN's eyewall warmed and loosened on May 17. It weakened into category 4 that afternoon, and turned north as it reached the western periphery of the subtropical ridge. Because of substantially lower sea temperatures and unfavourable upper-level environment, DOLPHIN weakened quite rapidly after recurvature. By early May 19, it was reduced to a marginal typhoon, still with relatively tight convections as it passed the Bonin Islands. The storm accelerated to around 30 km/h during the day and started extratropical transition. It turned extratropical on May 20 in the Pacific east of Japan.
繼較早時紅霞增強為五級超級颱風，白海豚成為於西北太平洋中，5 月第二個達到此強度的熱帶氣旋。一團對流於 5 月初於波納佩島以南發展，並於 7 日增強為熱帶低氣壓 07W。形成初期，07W 的對流集中在其外圍，預料需一段時間才能整合。雖然其外貌鬆散，但 8 日的風場分析顯示其中心有一圓形閉合的對流，風速達強風程度。
受低層西風影響，07W 於 7 及 8 日向東至東南偏東移動。由於風暴尺度較大，其增強速度初時極其緩慢。隨著西風減弱，07W 移速放緩，並沿副熱帶高壓脊的一細小弱點轉北移動。日本氣象廳於 9 日晚上 8 時將 07W 升格為熱帶風暴，並給予名稱白海豚。白海豚遂成西北太平洋有史以來最早的第 7 號熱帶風暴，比舊紀錄早了接近 10 天 (1971 年 5 月 19 日的熱帶風暴嘉娜)。當時預料白海豚將沿該弱點北移，稍後因副高增強而轉西。
白海豚於隨後兩天北移，但沒甚增強。它於 11 日在北緯約 10 度的地方停頓並轉西移，當時其環流中心仍然部分外露。風暴於 12 日開始以較快速度增強，有組織的對流終能包圍風暴中心，使白海豚的結構更為對稱。白海豚被升格為強烈熱帶風暴，並於 13 日進一步被升格為颱風。路徑方面，白海豚開始向西北偏西移動，並加速至每小時約 20 公里。
風暴於 13 日發展出一針眼，但持續不久後便崩潰。白海豚受較乾空氣入侵，但隨著其結構變得緊密而且尺度縮小，乾空氣的影響相對輕微。同時，受惠於垂直風切變下降，白海豚於 15 日繼續增強，並於當天掠過關島以北，當地錄得颶風。經過關島後不久，白海豚開始快速增強，並發展出堅固環狀的眼牆，內裡嵌有一直徑約 50 公里的風眼。聯合颱風警報中心於 16 日下午 2 時將白海豚升格為超級颱風 (130 節 / 每小時 241 公里)，並於 12 小時後上調其強度至 140 節 (每小時 259 公里)，即五級超級颱風強度。雖然其巔峰強度與紅霞相同，但白海豚的外貌明顯較差，其眼牆雲頂溫度不時高於 -70 度，風眼亦未像紅霞般清晰1。日本氣象廳則估計白海豚的最高強度為 100 節 (每小時 185 公里)，中心氣壓 925 百帕斯卡。
白海豚的眼牆於 17 日變暖及變得較為鬆散，於當天下午減弱為四級颱風。同時，白海豚到達副高西沿，因此風暴轉向北移。由於海水明顯變冷及高空大氣環境轉差，白海豚於轉向後減弱速度頗快，於 19 日只餘颱風強度下限。風暴於同日掠過小笠原群島，當時其對流仍相對緊密。白海豚於當天加速至約每小時 30 公里，並開始溫帶氣旋轉化。它於 20 日在日本以東的太平洋轉化為溫帶氣旋。
1Because of such lack of stability, HKWW did not upgrade DOLPHIN into a category 5 super typhoon.
1由於白海豚的型態欠穩，本站並未將其升格為五級超級颱風。
| Figures 圖片 |
Figure 1 - Satellite image of DOLPHIN at formation
圖 1 - 白海豚形成時之衛星雲圖
Figure 2 - Wind field analysis on May 8 showing a well-defined low-level circulation centre
圖 2 - 5 月 8 日的風場分析可看到一個清晰的低層環流中心
Figures 3a and 3b - Steering flow charts at 8 am May 11 (left) and May 17 (right)
圖 3a 及 3b - 5 月 11 (左) 及 17 日 (右) 上午 8 時之駛流圖
Figures 4a and 4b - Forecast tracks from different agencies on May 10 (left) and May 16 (right)
圖 4a 及 4b - 5 月 10 (左) 及 16 日 (右) 各氣象台之預測路徑圖
Figure 5 - DOLPHIN developed a pinhole eye on May 13
圖 5 - 白海豚於 5 月 13 日發展出一針眼
Figure 6 - Radar image of DOLPHIN as it nears Guam
圖 6 - 白海豚靠近關島時之雷達圖
Figure 7 - Satellite image of DOLPHIN at peak intensity
圖 7 - 白海豚於巔峰強度時之衛星雲圖
Figure 8 - DOLPHIN's estimated wind field at 8 am May 17
圖 8 - 白海豚於 5 月 17 日上午 8 時之估算風場圖
| Other Data 其他數據 |
Table 1: Track data from HKWW:
表一 : 香港天氣觀測站之路徑資料
| YYMMDDZZ Lat Long Wind 15050618 045N1585E 025 15050700 042N1590E 025 15050706 038N1599E 030 15050712 036N1606E 030 15050718 034N1611E 030 15050800 036N1618E 030 15050806 039N1620E 030 15050812 040N1622E 035 15050818 042N1622E 035 15050900 045N1623E 035 15050906 047N1623E 035 15050912 050N1623E 035 15050918 056N1618E 040 15051000 062N1605E 040 15051006 068N1600E 040 15051012 076N1600E 040 15051018 084N1599E 040 15051100 093N1599E 040 15051106 098N1599E 040 15051112 100N1592E 045 15051118 100N1587E 045 15051200 102N1584E 045 15051206 101N1581E 045 15051212 099N1575E 045 15051218 099N1569E 050 15051300 101N1562E 060 15051306 103N1554E 070 15051312 106N1542E 080 15051318 110N1535E 080 15051400 115N1521E 080 15051406 120N1511E 080 15051412 125N1496E 080 15051418 127N1483E 080 15051500 133N1471E 080 15051506 136N1455E 085 15051512 140N1445E 090 15051518 148N1434E 105 15051600 152N1425E 115 15051606 158N1415E 130 15051612 165N1406E 135 15051618 172N1398E 135 15051700 179N1391E 135 15051706 186N1387E 130 15051712 194N1385E 125 15051718 201N1384E 120 15051800 209N1385E 110 15051806 217N1386E 100 15051812 222N1388E 090 15051818 232N1391E 080 15051900 239N1394E 075 15051906 246N1400E 070 15051912 257N1410E 070 15051918 269N1423E 065 15052000 280N1441E 060 |
Table 2: Track data from JTWC:
表二 : 聯合颱風警報中心之路徑資料
ID Name YYMMDD ZZZZ Lat Long Basin Wind Pres 07W DOLPHIN 150519 0000 24.0N 139.2E WPAC 75 967 |
Last Accessed 最近訪問日期: Sun Sep 08 2024 12:36:50 HKT
Last Modified 最近修訂日期: Mon Jul 24 2023
