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Post by duwayne on Feb 21, 2019 17:23:39 GMT
ENSO index is an anomaly based upon a "centered" 30 year base period updated every 5 years. The base period of the current ENSO is estimated based upon the past 30 years so over the next approximate 15 years its subject to some change. This can cause el ninos and la ninas to disappear or appear over time when the record is close. So for example if the current neutral conditions don't result in an official el nino, some time in the future if cooling sets in as predicted by Astromet an El nino could emerge after the fact. I am sure Astromet would have some nice things to say about that. Living with limited looks here also. Duwayne. I was scanning the MEI pages and found this. Thought you might be interested. El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales. Here we attempt to create a reliable ENSO index for much of the historical record by basing the extended Multivariate ENSO Index (MEI.ext) on the two main observed variables over the tropical Pacific that have been reconstructed by the Hadley Centre back to 1871. These two variables are: sea-level pressure (P; details in Allan and Ansell, 2006), and sea surface temperature (S; details in Rayner et al., 2006). Similar to the original MEI, the extended MEI.ext is computed separately for each of twelve sliding bi-monthly seasons (Dec/Jan, Jan/Feb,..., Nov/Dec). Since the original Hadley Centre data are already pre-filtered, the MEI.ext is calculated directly from the gridded fields as the first unrotated Principal Component (PC) of both P and S. This is accomplished by normalizing the total variance of each field first, and then performing the extraction of the first PC on the co-variance matrix of the combined fields (Wolter and Timlin, 2011). The figure above is taken from this paper and shows the bimonthly values of the MEI.ext, standardized with respect to each season, and to the 1871-2005 reference period. Caution should be exercised when interpreting the MEI.ext on a month-to-month basis, since it was developed mainly for research purposes, similar to the original MEI. Negative values of the MEI.ext represent the cold ENSO phase, a.k.a. La Niña, while positive MEI.ext values represent the warm ENSO phase (El Niño). www.esrl.noaa.gov/psd/enso/mei/Missouriboy, thanks for the info. It would seem from the description that the MEI values are not detrended and therefor are inflated to some extent by the overall background increase in sea surface temperatures. From Icefisher's post above, it appears the ENSO index is not detrended although the baseline is updated every 5 years so the background change is relatively small.
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Post by icefisher on Feb 21, 2019 19:31:57 GMT
Duwayne. I was scanning the MEI pages and found this. Thought you might be interested. El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales. Here we attempt to create a reliable ENSO index for much of the historical record by basing the extended Multivariate ENSO Index (MEI.ext) on the two main observed variables over the tropical Pacific that have been reconstructed by the Hadley Centre back to 1871. These two variables are: sea-level pressure (P; details in Allan and Ansell, 2006), and sea surface temperature (S; details in Rayner et al., 2006). Similar to the original MEI, the extended MEI.ext is computed separately for each of twelve sliding bi-monthly seasons (Dec/Jan, Jan/Feb,..., Nov/Dec). Since the original Hadley Centre data are already pre-filtered, the MEI.ext is calculated directly from the gridded fields as the first unrotated Principal Component (PC) of both P and S. This is accomplished by normalizing the total variance of each field first, and then performing the extraction of the first PC on the co-variance matrix of the combined fields (Wolter and Timlin, 2011). The figure above is taken from this paper and shows the bimonthly values of the MEI.ext, standardized with respect to each season, and to the 1871-2005 reference period. Caution should be exercised when interpreting the MEI.ext on a month-to-month basis, since it was developed mainly for research purposes, similar to the original MEI. Negative values of the MEI.ext represent the cold ENSO phase, a.k.a. La Niña, while positive MEI.ext values represent the warm ENSO phase (El Niño). www.esrl.noaa.gov/psd/enso/mei/Missouriboy, thanks for the info. It would seem from the description that the MEI values are not detrended and therefor are inflated to some extent by the overall background increase in sea surface temperatures. From Icefisher's post above, it appears the ENSO index is not detrended although the baseline is updated every 5 years so the background change is relatively small. Its probably worth some research as to what really is going on. I gave the official "on top" answer. But it seems that for a few years a few years ago there was a large discrepancy between what was reported on a weekly basis and what actually ended up as the "seasonal" mean. My guess was that with a warming trend estimated at .2degC per decade, the .3 degree discrepancy i had been observing had something to do with temporary seasonal results being much cooler than the weekly reported results. I haven't followed this for a couple of years because of being too busy but a quick look suggests maybe that bias has been eliminated because the current ENSO departure compiled for the past year in the weekly status evolution report matches the "official" historic record. Perhaps this has been fixed by uniformly applying a projected future warming over the second half of what will be the final baseline to both the historic results and the operational data. But thats just a guess. If they are projecting a warming trend into the future in the modeling what happens if Astromet turns up being correct about impending cooling? That could make for even bigger errors than what they have already experienced via projecting warming rather than cooling.
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Post by acidohm on Feb 27, 2019 20:10:59 GMT
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Post by nautonnier on Feb 27, 2019 20:41:22 GMT
Well the loop current is looking a little more healthy The sea to the delicate sensibilities of someone living in FL is _frigid_ at 65F (Feb mean is 70F) so how it manages to get so hot by flowing up past 'The Great White North' I don't know.
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Post by missouriboy on Feb 27, 2019 21:04:47 GMT
Well the loop current is looking a little more healthy The sea to the delicate sensibilities of someone living in FL is _frigid_ at 65F (Feb mean is 70F) so how it manages to get so hot by flowing up past 'The Great White North' I don't know. It is an anomaly after all. Could be that all that warmer water that has been being packed in depth into the west Atlantic as the remainder goes cold is being slowly forced to the surface as it sheds its heat to the atmosphere. It's the only thing holding up the AMO.
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Post by Ratty on Mar 14, 2019 22:30:04 GMT
What is that tongue of cold water, a Panama-induced La Nina?
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Post by fatjohn1408 on Mar 14, 2019 23:32:30 GMT
What is that tongue of cold water, a Panama-induced La Nina? I went for a pee.
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Post by nautonnier on Mar 15, 2019 1:31:57 GMT
What is that tongue of cold water, a Panama-induced La Nina? Considering that the antipodes are at the end of their summer - there is a lot of cold around down there.
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Post by nonentropic on Mar 15, 2019 3:54:48 GMT
this is an anomaly map so the cold in that plume is in fact more a constant temperature. But very unexpectedly cold. lets see what happens.
yes it quite cold in the southern hemisphere but not everywhere. We in New Zealand are enjoying a spell of warm water around us and consequent warm air. the headless chickens are bleating heat and lemmings rule.
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Post by Ratty on Mar 15, 2019 5:14:50 GMT
What is that tongue of cold water, a Panama-induced La Nina? I went for a pee. Make a doctor's appointment .... now!
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Post by Ratty on Mar 15, 2019 5:17:54 GMT
What is that tongue of cold water, a Panama-induced La Nina? Considering that the antipodes are at the end of their summer - there is a lot of cold around down there. ... and we're at the tail end of yet another heatwave here in SE QLD and fairly warm in a few other places ...
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Post by nautonnier on Mar 15, 2019 10:23:41 GMT
Considering that the antipodes are at the end of their summer - there is a lot of cold around down there. ... and we're at the tail end of yet another heatwave here in SE QLD and fairly warm in a few other places ... Atmospheric heat is heat on the way out of the system. So yes both New Zealand and West Island are by the open door as the heat rushes out to space.
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Post by Ratty on Mar 15, 2019 11:42:36 GMT
... and we're at the tail end of yet another heatwave here in SE QLD and fairly warm in a few other places ... Atmospheric heat is heat on the way out of the system. So yes both New Zealand and West Island are by the open door as the heat rushes out to space. Could we make it rush out more quickly, please?
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Post by nautonnier on Mar 15, 2019 11:50:46 GMT
Atmospheric heat is heat on the way out of the system. So yes both New Zealand and West Island are by the open door as the heat rushes out to space. Could we make it rush out more quickly, please? I'll quote you when you complain about the noise from the frost fair on the Brisbane river.
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Post by Ratty on Mar 15, 2019 11:53:57 GMT
Could we make it rush out more quickly, please? I'll quote you when you complain about the noise from the frost fair on the Brisbane river. I'll laybuy those ice skates now. How long do you think I will need to pay them off?
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