Friday, June 12, 2009

Delayed - Part I

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

As I typed on 6 June, my next discussion will not be until the weekend of 26-28 June. The global circulation is weakly tilted toward El-Nino; however, there are some mixed signals involving the weather-climate dynamical system. While tropical convective forcing "hangs back" across the region of Indonesia, a superimposed MJO signal is emerging into the Western Hemisphere. Perhaps there will be another loop in WH (2004) phase space during the next few weeks displaced toward octant 7. The WB (2009) measure of the GWO maintains its weak projection, given the recent persistent positive ~1 sigma global AAM anomaly (R1 data climatology) and minimal time tendency. Simply put, analogous to the current financial markets the GWO is moving sideways. Will this continue the remainder of boreal summer 2009?

A mixture of the snr composite anomaly plots for MJO phases 7-8 and GWO phases 8-1 loosely depicts the global atmosphere. With variations, this situation may continue going well into July. Interestingly, anomalous upper tropospheric anticyclones are starting to dominate the Southern Hemisphere subtropical atmosphere (austral winter), arguably bearish. Stay tuned!

Please see links from the 6 June posting for real-time infomation, and email me/post comments if you have questions.

Ed Berry


snoman said...

Hi Ed,

It will certainly be interesting to see what happens if the current MJO wave eventually gets into octants one and two as the current ensemble forecast indicates. That could easily upset any momentum toward El Nino that is curently being observed. It has been very tempting to fully jump onto the El Nino bandwagon, but the OLR, AAM, and 200mb zonal winds have been reluctant to fully commit to it.

What an "upset" it would be if the El Nino fails!

I hope the projects you are working on are going well.


Ed Berry said...

Hello Jim,

Thank you for the comment. There is a respectable equatorial WWB coming out into the WPAC with the MJO having anomalies a good 5-10m/s (actual westerlies; per TAO data) ~140-160E. The equatorial Pacific Ocean basin is anomalously warm (all Nino regions; see TAO data), and overall the weather-climate dynamical system is tipped toward El-Nino. I suspect when the tropical forcing returns to the EH, it will propagate east fairly rapidly.

I think we will have to wait until this fall before there is a clearer ENSO signal. There are numerous issues, including that the subsurface is not particularly warm. Perhaps a decent oceanic Kelvin wave from this MJO may change this. Stay tuned!


Greg said...

Hello Ed,

I hope what ever you are working on turns out great, as all of your other works do.

I'm trying to piece things together here a bit. I noticed that the frictional torques are removing positive AAM anomalies in the tropics and mid-latitudes and since mountain torques respond to frictional torques, it is likely that we will see continued removal of postive AAM anomalies via mountain torque. Mountain torque dominates the other torques, and it is possible that we will see a dip in the relative AAM (eh, something like that).

So there appears to be a positive AAM relaxation in the coming days.

There has been strengthening of westerly winds in the EH (as noted by your last comment), but the 200mb winds still remain out of the east. Which makes the zonal mean winds a bit of a mix (I think).

Negative OLR anomalies persist in the west Pacific and Bay of Bengal. I remember you stated that EH tropical convection is ok as long as it doesn't become enhanced(it appears it hasn't).

Do those loosely touch upon the reasons for projecting a brief El-Nino respite to GWO phases 8-1 for the coming weeks?

Ed Berry said...

Hello Greg,

Sorry for my slow response. Essentially the weather-climate dynamical system is in a quasi-stationary/equilibrium state weakly shifted toward El-Nino. The large negative global frictional torque is partly a response to zonal mean subtropical westerly wind flow anomalies being brought down to the surface as they shift poleward. That has helped to persist global AAM ~1 standard deviation above the R1 data climatology (lower 21 sigma levels)since roughly mid-May.

The gist is that I think the global circulation will remain shifted toward octants 7-8-1 of GWO/MJO phase space UFN. What happens this fall will be critical. The EH tropical convection is not much more than
"normal rainfall" for the monsoon systems. In fact, until a few days ago the situation there was "dry". The surface westerlies/upper tropospheric easterlies you refer to are to be expected with a first order baroclinic mode to tropical forcing.

Hope this helps,

Greg said...

Hi Ed,

Thank you for the response. Your dedication is much appreciated.


snoman said...

I am really beginning to think the El Nino has a rough road ahead. The GFS and ECMWF models indicate a massive high pressure complex setting up over a good chunk of the central and eastern North Pacific. Such an arrangement would make strong trade winds quite likely.