AtmosSci

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標 題: 2005一篇science上的文章
發信站: 批踢踢實業 (03/29/06 09:43:50 Wed)

這是在2005/9science期刊上的一篇論文
(Webster et al, Science 309, 5742, 2005)

其中提到了全世界cat 4 and 5的颶風(所有颱風 颶風 暴風什麼的通通加在一起)
在近三十年來的數量和比例暴增了兩倍左右
http://www.sciencemag.org/cgi/content/full/309/5742/1844

下面節錄一些文字給大家看看(有興趣的可以去下載 不過一般家中應該看不到)

摘要部分:

We examined the number of tropical cyclones and cyclone days as well as
tropical cyclone intensity over the past 35 years, in an environment of
increasing sea surface temperature. A large increase was seen in the number
and proportion of hurricanes reaching categories 4 and 5. The largest
increase occurred in the North Pacific, Indian, and Southwest Pacific Oceans,
and the smallest percentage increase occurred in the North Atlantic Ocean.
These increases have taken place while the number of cyclones and cyclone
days has decreased in all basins except the North Atlantic during the past
decade.

上面還蠻簡單的 應該不太需要翻譯 重點是說在海溫升高的情形之下
4 5級颶風的比例大幅提昇 不管在哪一個洋面 而以北太平洋 印度洋 南太平洋增加最兇
而以北大西洋增加較緩(去年是在嗆聲嗎@@?)
但風暴的數目和日數卻出現下降的狀況(除了北大西洋)

內文重點摘錄

Tropical ocean SSTs increased by approximately 0.5°C between 1970 and 2004
這就是說海溫上升了 0.5度

Examination of hurricane intensity (Fig. 4) shows a substantial change in the
intensity distribution of hurricanes globally. The number of category 1
hurricanes has remained approximately constant (Fig. 4A) but has decreased
monotonically as a percentage of the total number of hurricanes throughout
the 35-year period (Fig. 4B). The trend of the sum of hurricane categories 2
and 3 is small also both in number and percentage. In contrast, hurricanes in
the strongest categories (4 + 5) have almost doubled in number (50 per pentad
in the 1970s to near 90 per pentad during the past decade) and in proportion
(from around 20% to around 35% during the same period). These changes occur
in all of the ocean basins. A summary of the number and percent of storms by
category is given in Table 1, binned for the years 1975–1989 and 1990–2004.
This increase in category 4 and 5 hurricanes has not been accompanied by an
increase in the actual intensity of the most intense hurricanes: The maximum
intensity has remained remarkably static over the past 35 years

這段就是重點了 在過去35年來呢 1級颶風的數量看起來變化不是很大
但比例有下降的趨勢(但看圖數量也有下降趨勢)
2+3級颶風的比例改變不大

但4+5級這種頂級颶風 數量和比例卻是大幅上升
在70年代每五年會有50個左右的五級颶風 但到了90年代每五年卻有高達90個左右了!
而在比例方面也是大大提升 從大約20%升高到了35%

論文中的圖片給大家參考
http://tinyurl.com/gmplw (海溫部分)
http://tinyurl.com/j26dc (各等級颶風數量和比例變化 改變真是超大)

有一張表給大家參考(論文中的) 這是4+5級颶風的比例

Basin Period

1975~1989 1990~2004

數量 比例 數量 比例

EPAC(東北太平洋) 36 25% 49 35

WPAC(西北太平洋) 85 25 116 41 (我們所在的...orz 41%@@)

NATL(北大西洋) 16 20 25 25

SWPAC(西南太平洋) 10 12 22 28 (增加很多)

NIO(北印度洋) 1 8 7 25 (數量增加七倍XD)

SIO(南印度洋) 23 18 50 34 (這也增加的非常驚人)


那麼去年2005年的情形呢？

稍微整理一下 (由於上述表格是把tropical strom等級排除在外 所以以下整理也相同)

WPAC部分 4+5級有9個 佔56%

EPAC部分 4+5只有1個 佔14%

NATL部分 4+5級有5個 佔33%

NIO去年沒有hurrican等級的風暴出現

SIO和SWPAC不太好分 兩個加起來算 有7個 佔64%(好猛...orz)

總共有22個4+5級颶風 佔總數45%




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