orographic effects on a squall line system over taiwan jen – hsin teng, ching – sen chen, and...
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![Page 1: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/1.jpg)
Orographic Effects on a Squall Line System over
Taiwan
JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG,
YI-LENG CHEN
2003 年 12 月 16 日 野村真奈美
(MONTHLY WEATHER REVIEW
APRIL 2000)
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Introduction
TAMEX
・ Orographic effects・ Linear convective lines・ Squall line systems
Studied in different parts of the world
CMR
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Previous studies have focused on・ The structural features・ The reason for maintenance in squall line’s mature stage
Squall line systems
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Objective
To study orographic influence on the evolution of a fast-moving squall line system ・ the structure ・ internal circulation of the squall line system・ the prestorm environmental flow・ the low-level moisture flow from the frontData sources and analysis
proceduresSoundings, Surface, and radar data
Wang et al.(1990)
sounding
S-band
![Page 5: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/5.jpg)
A brief description a squall line system over Taiwan
Wang et al.(1990)
15.5m/s
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Evolution of radar echoes during landfall
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Horizontal cross sectionahea
dbehind
0130 LST
The low level
The middle level
20dbZ
>30dbZ
>3m/s
>6m/s
1500m
η= 0.05 η= 0.35
![Page 8: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/8.jpg)
0137 LSTThe squall line’s southern
portion encountered higher terrain
The low level
The middle level
20dbZ
>30dbZ
>3m/s
>6m/s
1500m
η= 0.05 η= 0.35
![Page 9: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/9.jpg)
0207 LST
The squall line moved over the mountainous areas
20dbZ
20dbZ
>30dbZ
1500m
The low level
The middle levelη= 0.05 η= 0.35
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0130 LST
Vertical cross section
Ⅰ.The mountain ridge areas
Gust front
11.5m/s
15m/s
12km
3
Fig8.a
Fig5.a
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つづき
Vertical cross section
Ⅰ.The mountain ridge areas
Fig6. a
014301370130
0130LST のガストフロント
0137LST
0143LST
Fig8. b,c,f
9.5km
![Page 12: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/12.jpg)
つづき
Ⅰ.The mountain ridge areas
Vertical cross section
0207LST
0154LST
The deceleration of the squall line by the terrain affected the overall storm’s circulation pattern.
Fig8.d
Fig8.e
Fig7.a
8.5km
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Ⅱ.The mountain valley areas
Vertical cross section
0130LST
0137LST
Fig5.a
Fig9.a
Fig9.b
13.6m/s
12km
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つづき
Ⅱ.The mountain valley areas
Vertical cross section
The deceleration of the squall line by the terrain affected the overall storm’s circulation pattern.
0143LST
0154LST
0207LST
Fig7.a
Fig9.c
Fig9.d
Fig9.e
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Discussion
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Summary & Conclusions
TAMEX 期間中に観測された南北に走向を持つスコールラインが山岳を通過する際のシステムの発達過程を調べた
上昇流の傾きが垂直に変化山岳によってシステムが減速する
前面からの inflow の層が薄くなる700hPa (高度 3km )付近に最大値を持つ南西からシステムに流入する inflow が主要なものになるスコールラインの後ろにある南西風が山に衝突システムの鉛直運動は地形による強制上昇と潜熱の放出が卓越する
下層の moisture front to rear inflow の減少
地形の効果によるスコールラインシステムの急速な消失
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Summary & Conclusions
TAMEX 期間中に観測された南北に走向を持つスコールラインが山岳を通過する際のシステムの発達過程を調べた・ the structure ・ internal circulation of the squall line system
・ the prestorm environmental flow
The tilted updraft westerly → vertical
・ the low-level moisture flow from the frontThe storm relative inflow
decreased.
parallel to the terrain →
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つづき
この一連の変化が 40 分という時間で起きましたとさ。
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相当温位Wang et al.(1990)
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Evolution of radar echoes during landfall
![Page 21: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/21.jpg)
その他 Wang et al.(1990)
Wang et al.(1990)
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Wang et al.(1990)
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0130 LST
Vertical cross section
0137 LST
15km
9km
Ⅰ.The mountain ridge areas
Fig5. a
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S
15.5 m/s
NNE
Z = 3km
SW
A brief description a squall line system over Taiwan
![Page 25: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/25.jpg)
Vertical d
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つづき
Fig8. f
Vertical cross section
Ⅰ.The mountain ridge areas
Gust front
Fig8. c
Fig5. a
Fig8. e
The deceleration of the squall line by the terrain affected the overall storm’s circulation pattern.
![Page 27: Orographic Effects on a Squall Line System over Taiwan JEN – HSIN TENG, CHING – SEN CHEN, AND TAI-CHI CHEN WANG, YI-LENG CHEN 2003 年 12 月 16 日 野村真奈 美 (MONTHLY](https://reader036.vdocuments.site/reader036/viewer/2022062305/56649d395503460f94a133af/html5/thumbnails/27.jpg)
つづき
Ⅰ.The mountain ridge areas
Vertical cross section
The deceleration of the squall line by the terrain affected the overall storm’s circulation pattern.
0207LST
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とりあえず出来事は
下層で leading edge (南ー北方向) が谷側で凸状になる
上層はあまり地形の影響を受けない
上昇運動の西側への傾きは山に向かうにつれて小さくなる
下層( 1 ~ 4km )の flow ( from the rear ) は上昇流に入っていく
Leading edge の後ろの cold pool が斜面に沿ってあがっていく
鉛直運動は地形によって強化・潜熱の放出
高い山に近づくと、より地形に沿った鉛直運動になる風下側に下降運動を伴う
スコールラインが消滅したときには山の頂上付近で持ち上げによる弱いエコーがみられた
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弱まった原因?
スコールラインの前面の
下層の環境風 → (地形のブロック)
Mountain ridges 弱い南風 < Mountain valleys 弱い南西風 システムに相対的な下層の 前→後 flow は弱いでも、山側も谷側も下層の湿潤な前面からのinflow は急激に減少している
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Gust front
15km
0130 LST
Vertical cross section
9km
0137 LST
Ⅰ.The mountain ridge areas
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Summar
y
The drastic effects of steep terrain on a fast-moving squall-line system resulted in
the rapid dissipation of the system.
Orographic influence on the evolution of a fast-moving squall line system was
investigated.