TC Watch / 熱帶氣旋 > Selected TC Review / 重要熱帶氣旋回顧 > 201517W (ATSANI 艾莎尼) [Refresh 更新]
 201517W (ATSANI 艾莎尼) - Profile 檔案 |
(Issued on October 3, 2015)
(於 2015 年 10 月 3 日發出)
Brief profile of ATSANI 艾莎尼小檔案:
| JTWC number 聯合颱風警報中心 (JTWC) 號碼 | 17W |
| International number 國際編號 | 1516 |
| Period of existence 生存時期 (JTWC) | 2015/08/14 14 HKT - 2015/08/26 08 HKT |
| Lifetime 壽命 (JTWC) | 11.75 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 ATSANI 本站有關艾莎尼的發佈 |
Please click here for bulletins on ATSANI. 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)
ATSANI developed in a complex steering environment in the middle of August. The JTWC issued a tropical cyclone formation alert for the system (98W) early on August 14. At that time, another disturbance was picking up strength some 1500 km west of 98W, which eventually became tropical cyclone 16W/GONI. The two systems were generally moving in the southern periphery of the subtropical ridge; there was also influence from the equatorial ridge southeast of 98W, resulting in its slow movement in the first few days of formation.
98W was upgraded into tropical depression 17W in the afternoon of August 14. Slow movement was predicted initially because of the aforementioned reasons, and a gradual turn to the northwest was expected as the subtropical ridge would then reorient and build to the east of 17W. Substantial intensification was also expected due to the combined favourable conditions along its forecast track. On the other hand, the JMA upgraded 17W into a tropical storm at 2 am August 15, at which point 16W was also upgraded. The JMA followed the order of gale warnings issued to the two cyclones, and therefore named 16W GONI and 17W ATSANI.
ATSANI moved westward on August 15 and August 16, with some southward dip as the subtropical ridge extended south briefly just west of ATSANI. The storm also consolidated its peripheral convections and showed decent cloud signature on August 16. It reached severe tropical storm strength on the same day, and was upgraded into a typhoon that night.
As the subtropical ridge reoriented, ATSANI turned WNW on August 17. A ragged eye could be seen on satellite images, which shrank in size on August 18 as its central dense overcast expanded. It turned northwest later that day and continued to intensify. ATSANI reached super typhoon status (130 knot / 240 km/h 1-minute average sustained winds) in the morning of August 19, while JMA's estimated strength was 95 knots (176 km/h) at that time. While ATSANI's eye enlarged again, its central dense overcast seemed to have shrunk slightly in width. Nevertheless, its eyewall cloud top temperatures dropped and reached -70 degrees uniformly around the eye that night. The JTWC upgraded ATSANI into a category 5 equivalent system with an estimated intensity of 140 knots (259 km/h). The JMA's maximum intensity was at 100 knots (185 km/h).
Towards the midnight of August 20, ATSANI's northern circulations weakened and its eyewall warmed considerably. The JTWC lowered its intensity estimate to 135 knots (250 km/h), meaning the storm had stayed at category 5 for just 6 hours. Sea temperatures started to drop as ATSANI moved north and this further impacted its development. The subtropical ridge started to retreat on August 21, allowing ATSANI to turn poleward just east of Chichi Jima. The storm was still able to maintain a large and clear eye, but its central dense overcast became warmer and thinner over time.
ATSANI turned northeast on August 23. It started to accelerate along the northwestern periphery of the subtropical ridge and began extratropical transition on August 24. Subject to strong vertical wind shear, ATSANI's circulation was distorted and it became fully extratropical late on August 25, still packing storm force winds at that time.
艾莎尼於 8 月中在較為複雜的駛流環境中形成。聯合颱風警報中心於 14 日早段對該系統 (98W) 發出熱帶氣旋形成警報，而與此同時，98W 以西約 1500 公里外有另一擾動發展，它最終成為熱帶氣旋 16W (天鵝)。當時兩個系統大致沿副熱帶高壓脊南部移動，但 98W 東南部同時有一赤道高壓脊，令其於形成首數天移動較為緩慢。
98W 於 14 日下午被升格為熱帶低氣壓 17W，預料初時移動緩慢，其後因副高型態改變並於風暴東面發展而開始向西北移動。由於預測路徑一帶大氣環境良好，17W 被認為會明顯增強。另一邊廂，日本氣象廳於 15 日凌晨 2 時同時將兩個系統升格為熱帶風暴，並按照為它們發出烈風警報的先後次序而將 16W 及 17W 分別命名為天鵝及艾莎尼。
艾莎尼於 15 及 16 日西移。由於副高於艾莎尼以西南伸，風暴亦略為南移。同時，艾莎尼整合其外圍環流，至 16 日其雲捲型態已成形。它於當天達到強烈熱帶風暴強度，並於晚間被升格為颱風。
隨著副高型態改變，艾莎尼於 17 日向西北偏西移動。它發展出一不規則風眼，並隨中心密集雲區於 18 日增厚而縮小。艾莎尼於當天較後時間開始向西北移動並繼續增強，於 19 日早上達到超級颱風強度 (一分鐘平均持續風速 130 節 / 每小時 240 公里)，而日本氣象廳所估算的強度則為 95 節 (每小時 176 公里)。艾莎尼的風眼再次變大，但其中心密集雲區似乎稍為變薄。雖然如此，其眼牆雲頂溫度繞風眼側均勻地下降，於晚間到達 -70 度。聯合颱風警報中心將其估算強度提升至 140 節 (每小時 259 公里)，即五級超級颱風強度。日本氣象廳當晚所給予的最高強度為 100 節 (每小時 185 公里)。
艾莎尼北面的對流於 20 日凌晨時份減弱，其眼牆明顯變暖。聯合颱風警報中心遂將其強度下調為 135 節 (每小時 250 公里)，意味著艾莎尼只有 6 小時達五級強度。海面溫度隨艾莎尼緯度增加而開始下降，令其發展受影響。副高於 21 日開始東退，令艾莎尼於父島以東北移。當時其風眼仍然大而清晰，但風暴中心密集雲區隨時間變得更暖更薄。
艾莎尼於 23 日轉向東北移動。它沿副高西北部加速，並於 24 日開始溫帶氣旋轉化。受強烈垂直風切變影響，艾莎尼的環流被扭曲。風暴於 25 日後段轉化為溫帶氣旋，當時其中心附近仍吹暴風。
| Figures 圖片 |
Figure 1 - Satellite image of ATSANI at formation
圖 1 - 艾莎尼初形成時之衛星雲圖
Figures 2a and 2b - Forecast tracks from official agencies on August 16 and 20
圖 2a 及 2b - 各官方氣象台於 8 月 16 及 20 日之預測路徑圖
Figures 3a and 3b - Steering flow charts on August 17 and 20
圖 3a 及 3b - 8 月 17 及 20 日之駛流場圖
Figure 4 - 500 hPa upper-level weather chart on August 18. Note the equatorial ridge and southward extension of the subtropical ridge between GONI and ATSANI.
圖 4 - 8 月 18 日之 500 百帕高空天氣圖，可見赤道高壓脊及副熱帶高壓脊於天鵝及艾莎尼間的向南延伸
Figure 5 - Satellite image of ATSANI at peak intensity
圖 5 - 艾莎尼達到巔峰強度時之衛星雲圖
Figure 6 - ATSANI's estimated wind field at 2 am August 20
圖 6 - 8 月 20 日上午 2 時艾莎尼之估算風場圖
Figure 7 - Satellite image on August 20 showing both GONI and ATSANI as significant typhoons
圖 7 - 8 月 20 日之衛星圖片顯示天鵝及艾莎尼均為強勁颱風
Figure 8 - ATSANI's wind field as it neared the Bonin Islands
圖 8 - 艾莎尼靠近小笠原群島時之風場圖
| 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 15081406 151N1630E 025 15081412 151N1623E 030 15081418 150N1621E 035 15081500 149N1621E 035 15081506 150N1621E 040 15081512 151N1620E 045 15081518 150N1614E 050 15081600 146N1609E 055 15081606 145N1605E 060 15081612 146N1599E 065 15081618 145N1594E 070 15081700 145N1592E 080 15081706 147N1584E 085 15081712 151N1580E 095 15081718 156N1571E 105 15081800 159N1562E 110 15081806 162N1554E 115 15081812 170N1548E 120 15081818 180N1538E 120 15081900 187N1529E 130 15081906 190N1519E 130 15081912 197N1513E 140 15081918 204N1504E 140 15082000 212N1495E 135 15082006 220N1486E 135 15082012 225N1478E 130 15082018 233N1471E 120 15082100 241N1465E 115 15082106 250N1460E 110 15082112 256N1455E 105 15082118 264N1453E 095 15082200 270N1449E 090 15082206 277N1450E 090 15082212 283N1451E 090 15082218 290N1452E 085 15082300 295N1454E 085 15082306 300N1460E 085 15082312 307N1467E 080 15082318 313N1474E 075 15082400 320N1481E 070 15082406 326N1492E 070 15082412 329N1508E 065 15082418 338N1528E 065 15082500 353N1556E 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 17W ATSANI 150826 0000 39.7N 162.2E WPAC 50 985 |
Last Accessed 最近訪問日期: Sun Sep 08 2024 12:45:37 HKT
Last Modified 最近修訂日期: Mon Jul 24 2023
