Global tropical SSTs are well above average from the East Pacific into the Atlantic Oceans with anomalies ~1-3C and totals near 30C south of
Latest 5-day averaged TAO buoy data indicates expanding subsurface warmth (~plus 3C) down to ~200m west of the date line and even 50m west of South America. However, regardless of what tools are believed to be useful, the interannual SST component including ENSO is unclear.
The following are links to global SST and related information.
http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)
Full disk satellite imagery and other aids do not indicate any concentrated region of enhanced tropical convective forcing. Instead, the most robust signal is the strong suppression covering much of the Indian Ocean into
Keying on the suppression as well as the 850mb and 200mb winds, the WH (2004) phase space plot indicates ~3 sigma projection (through 22 May) in octant 8. Even with the interannual component left in, the projection is still well over 2 standard deviations. There is other evidence to support what this equatorially confined empirically derived index is telling us, including the WB (2007, 08) GWO. The latter is a dynamical measure of the global circulation that links global-zonal mean-regional scale variations.
The point is that there is strong tropical-extratropical coupling once again occurring, including a very robust MJO signal in the
During this month, these anomalous equatorial westerlies (~5m/s zonal mean anomalies at 200mb) have propagated poleward and downward particularly into the Southern Hemisphere. Interactions with the midlatitude storm tracks including Rossby wave energy dispersions (RWDs) tied to Northern Hemisphere north-south mountain massifs led to the recent remarkable extension of the East Asian jet and ridge from Hell along the
As was expected probabilistically 2 weeks ago, there is currently frictional dissipation of the added westerly wind flow. The global frictional and mountain torques are strongly negative leading to a computed AAM tendency of ~minus 25 Hadleys. Much of that negative global AAM tendency has ~1-2 Hadley zonal mean contributions from the equatorial and subtropical atmospheres. Hence the GWO has orbited in phase space to octant 1 and a regional-scale response has been the retrogression of the “PNA ridge” into the eastern
As stated in previous postings, the WB (2007, 08) GWO, which considers the MJO and other tropical variability, offers a global dynamical weather-climate linkage framework to intelligently evaluate the numerical models. A couple of weeks ago the feeling was that the positive PNA
As tropical convective forcing returns to the Eastern Hemisphere during the next 1-3 weeks (with the MJO), the WB (2007,08) GWO is probable to circuit into phase 3 as zonal mean easterly wind flow anomalies increase in the tropical/subtropical atmospheres. Supportive are animations of fields such as 150mb daily mean vector wind anomalies. They indicate twin tropical anticyclones ~30-60W, with some “hints” of returning to the
Shifting northwest with the seasonal cycle, more periodic and anomalous western
Intense to severe thunderstorm activity is probable to spread east from equatorial Africa into the
An experimental quasi-phase space plot of the GSDM utilizing time series of normalized global relative AAM time tendency (Y-axis) and normalized global relative AAM anomaly (X-axis) can be found at
This phase plot is being re-done, as is the web site. Stay tuned. We call the behavior of this plot the Global Wind Oscillation (GWO). While the intent of the legacy GSDM is to extend current thinking beyond the MJO, the GWO quantifies variations used to derive the original GSDM in a manner that is “user friendly” analogous to the WH (2004) “convention”. In addition, the GWO plot does not have the ENSO signal removed.
Please see the revised description of the GSDM per above link. Also, I encourage the readers to study the annotated MJO and GWO phase space plots to help relate the global variations explained by those techniques to “weather”.
Links to CPC and PSD ENSO discussions:
The following is a link to information about the stratosphere and other nice monitoring tools:
The following is a link to NCEP model verifications (surf around for lots more).
These are probabilistic statements, and work is ongoing to quantify in future posts (for example, risk assessment maps, signal to noise ratio plots and shifts of probability). We hope that an opportunity will arise for us (soon) to have a dedicated web page effort to expedite more objectively, with rigor, thoroughness and verification.
The WB (2007) paper on the GSDM has been published in the February issue of MWR. In addition, a two-part paper is in ACTIVE preparation by WB that will formally introduce the GWO along with subseasonal composites for variables such as surface temperatures. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships.
Given shift work and travel, updates are extremely difficult. I should be able to post another discussion the weekend of 31 May – 1 June.