So What Really Has Changed?

Been talking about the weather patterns and what has changed and what has not really changed. Well one thing that we can all agree has changed has been the SSTS. But why have the SSTS changed? Have they changed because certain teleconnections have changed or could it be more of an El Nino bounce back?

HM describes it like this..

In my opinion, the cooling and rapid decline is mainly "El Niño bounce back" majorly induced by enhanced water vapor from the previous El Niño. Even though the numbers say otherwise, there is still an effect leftover in the atmospheric circulation/AAM. Since water vapor destroys ozone, incoming solar radiation has been generally reduced, despite weekly OLR anomalies that may represent positive values, and the heat energy of the water has been lost. The speed was perhaps further enhanced by the -QBO modulation (even further reduction in ozone/added -AAM) and decadal -PDO/AAM tedency to the climate.

He ends it with this..

So perhaps the swift drop was a nice timing of GCR increase in May, strong bounce back given water vapor/ozone, -PDO/AAM climate tendency and -QBO. Does this potentially mean that if some of these signals change that we just received a false La Niña signal or a false sense of the intensity expected?

So the above is something interesting to think upon in whether or not we are actually headed into a La Nina or what has happened has occurred due to the above mentioned occurrences.
So lets look at some teleconnections…

Lets start with the NAO

The NAO has been negative since October of 2009 and as of the latest reading which was April was still negative but not as negative as earlier.

The PNA

The PNA has been positive since June of 2009 in varying degrees of positiveness.

The AO

The AO has been negative since December of 2009 and as of April of 2010 that has continued as well..

So as one can see the NAO, PNA & AO all have not changed. They may have fluctuated in there degrees of intensity but the basis of the state has been the same.

CPC is the source for all this information

The one connection that has fluctuated the most is the EPO which has fluctuated back and forth from positive to negative.

What about the QBO?

The QBO has been negative since June of 2009 and has continued to get even more negative. Matter of fact it stands at –23.57 currently.

How about the PDO?

The PDO since Dec 09 has been neutral to positive and the most recent reading in April was still in the neutral to positive range at 0.78 which had climbed from its previously monthly reading.

The GlAAM ?

The GLAAM has been up and down but has also been mainly positive and once again after taking a dive negative has come back positive..

So evidence by what is posted above..the question really becomes what has really changed in the over all weather pattern that has been dominant?

What about La Ninas and Easterly QBOS? They are really not all that common. Basically when a La Nina happens and occurs it is when the QBO is in its westerly phase. There was a paper written in 1992 to that effect

Click Here –Gray

So with the QBO in its easterly phase and negative phase this really limits the likely hood of a La Nina.

Factor into the above this El Nino was an El Nino Modoki and since 1950 only two El Nino Modokis were followed by a La Nina.

So the question that started this off basically was has the pattern really changed since winter? The answer to this after doing some research is no. The same pattern that has been persistent continues to be. The teleconnections which were have remained in the same state of direction. The only thing that has fluctuated is the GLAAM and the EPO.

It should also be noted that a negative QBO in an easterly phase is also indicative and supportive of a negative NAO and blocking!

In conclusion the pattern has not really changed because the teleconnections are essentially the same. So what has changed?

The one thing that has changed is the ENSO itself..however..the reason for the change is up to discussion and debate. This is why Real Wx Services looks at things from a global perspective and not just the ENSO itself.

A paper written by Chris De Freitas says the following

“The surge in global temperatures since 1977 can be attributed to a 1976 climate shift in the Pacific Ocean that made warming El Niño conditions more likely than they were over the previous 30 years and cooling La Niña conditions less likely”