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[气候监测] 2010-2011年ENSO監察專帖

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发表于 2011-2-2 23:33 | 显示全部楼层
Strong La Niña event persists in the Pacific

澳大利亚气象局(Bureau of Meteorology)2月2日表示,澳大利亚近期遭遇的史上最严重的拉尼娜(La Nina)现象已经进入稳定期,有明确迹象显示,拉妮娜峰值已经过去,不过拉尼娜现象仍有一定概率持续2011年全年。

Issued on Wednesday 2 February 2011 | Product Code IDCKGEWWOO

Australia continues to feel the effects of one of the strongest La Niña's on record. During La Niña events, tropical cyclone numbers are typically higher than normal during the November to April period, while summer daytime temperatures are often below average, particuarly in areas experiencing excess rainfall.

Climate indicators of ENSO continue to indicate a strong, mature La Niña, although there are clear signs the event has passed its peak. Pacific Ocean temperatures have increased, especially below the surface, while atmospheric indicators such as the Southern Oscillation Index (SOI), trade winds and cloud patterns have eased from their peaks reached about a month ago.

                               
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These observations are consistent with long-range forecast models surveyed by the Bureau which show the Pacific gradually warming during the southern autumn. Given that March to June is the ENSO transition period, there is a spread among the model predictions for the middle of 2011. The most likely outcome is for a return to neutral conditions, but there is a chance of La Niña persisting for the rest of the year.

                               
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The influence of the Indian Ocean Dipole (IOD) on Australian rainfall is limited during the months from December through to April.
发表于 2011-2-4 14:30 | 显示全部楼层
从目前的海气状况演变和天文状况来看,出现连续3年强拉尼娜的可能性极高,当然这只是臆测而已,还是需要看实况的,历史会重演,当然不会是简单的重演,夏季防台,防高温;冬季防寒的工作依然不能松懈。
发表于 2011-2-4 14:56 | 显示全部楼层
连续3年是每年都出现新的拉尼娜过程还是现有拉尼娜事件持续到2012呢?NOAA的ENSO观测报告负责人Klaus.Wolter也看好这次La Nina持续到年底。不知天文状况指的是什么指标?地球自转速率么?
发表于 2011-2-4 15:56 | 显示全部楼层
从2010年持续到2012年,相似的历史状况可见73年-75年的拉尼娜,无论是SOI指数还是次表层海温状况,其相似性极强。太平洋年际振荡也似乎有利于拉尼娜的持续。而天文状况指的是黑子数,按NOAA对24周期黑子数的预测看,两者也似有异曲同工之妙。当然最终还是要看实况的,从历史中可能可以推测未来,这正是奇妙之处啊!
发表于 2011-2-5 11:25 | 显示全部楼层
http://www.esrl.noaa.gov/psd/people/klaus.wolter/MEI/#discussion
By Klaus.Wolter@noaa.gov

                               
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In the context of the rapid transition of the MEI into strong La Niña conditions, this section features a comparison figure with strong La Niña events that all reached at least minus one standard deviations by June-July, and a peak of at least -1.4 sigma over the course of an event. The most recent moderate La Niña events of 1998-2001 and 2007-09 did not qualify, since they either did not reach the required peak anomaly (the first one) or became strong too late in the calendar year (both).

The updated (December-January) MEI value has strengthened slightly to -1.62 standard deviations after almost dropping below -2 standard deviations in August-September. Nevertheless, the most recent value ranks 2nd for this time of year, clearly below the 10%-tile threshold for strong La Niña MEI rankings , but slightly weaker than the value recorded in 1974. If one were to take the average of all MEI rankings since July-August (a six-month period), the strongest La Niña half-year periods of mid-55, '73-74, and late '75 averaged slightly stronger than the current event, for now (this is means Rank 4 for the current event, up one from last month).

Negative SST anomalies are covering much of the eastern (sub-)tropical Pacific in the latest weekly SST map. Many of these anomalies are in excess of -1C.

For an alternate interpretation of the current situation, I highly recommend reading the latest NOAA ENSO Advisory which represents the official and most recent Climate Prediction Center opinion on this subject. In its latest update (6 January 2011), La Niña conditions are expected to last "well" into the Northern Hemisphere spring of 2011.
Stay tuned for the next update (by March 5th) to see where the MEI will be heading next. While La Niña conditions are guaranteed well into 2011, it remains to be seen whether it can rally once more to cross the -2 sigma barrier, and/or whether it will indeed last into 2012, as discussed six months ago on this page. I believe the odds for a two-year event remain well above 50%, made even more likely by the continued unabated strength in various ENSO indices.
发表于 2011-2-6 14:43 | 显示全部楼层
拉尼娜有强度越强持续时间就越长的特点,与强厄尔尼诺通常只持续一年,而弱厄尔尼诺有些会持续多年相反,1876年来持续时间达到3年的拉尼娜共有5次,分别是1878-1881年,1915-1918年,1954-1957年,1973-1976年,1998-2001年,都是历史上最强的拉尼娜
发表于 2011-2-12 15:20 | 显示全部楼层
68# phoonfan


同样,强圣婴现象也可持续较长时间,如1982-1983年,1997-1998年。
发表于 2011-2-16 18:21 | 显示全部楼层
http://www.bom.gov.au/climate/enso/
La Niña event now passed its peak
澳洲气象局估计此拉尼娜已过强度顶峰,多数模型估计到6、7月将恢复正常,少数模型估计将持续到8月以后

                               
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Issued on Wednesday 16 February 2011 | Product Code IDCKGEWWOO

The La Niña event which has dominated the Australian climate for the past nine months is showing signs of weakening. Pacific Ocean temperatures, most notably below the surface, have warmed, while atmospheric indicators such as the Southern Oscillation Index (SOI), trade winds and cloud patterns have eased from their respective peaks in early January.

These observations are consistent with both the life cycle of past La Niña events and long-range climate models, which show the Pacific gradually warming during the southern autumn of 2011. All available climate models suggest further weakening of the La Niña is likely through autumn, with most indicating a return to neutral conditions by winter 2011. However, there remains some risk that the event may reform after autumn.

                               
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During La Niña events, tropical cyclone numbers are typically higher than normal during the November to April period, with February and March the peak. The influence of La Niña on Australian rainfall and temperature typically peaks during winter to mid-summer, and then weakens during the following autumn.

The influence of the Indian Ocean Dipole (IOD) on Australian rainfall is limited during the months from December through to April.
 楼主| 发表于 2011-2-17 22:10 | 显示全部楼层
16 Feb 2011        1014.53        999.20        50.87        16.61        21.30
17 Feb 2011        1015.33        999.05        55.43        18.13        21.71

Carlos 暴力抬高SOI
发表于 2011-2-19 00:04 | 显示全部楼层
看来这个指标也不是很靠谱啊,居然让一个台风就改写了
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