Sunday, December 15, 2019

Will the West Pacific trade winds die down around January 4th 2020?

The following figure shows that the West Pacific trade winds died down around the 17th of September 2019 and two tropical months (i.e. 56.4 days) later around 10th of November 2010.


Just prior to these two dates, a hybrid combination of an Equatorial Rosby wave and Equatorial Kevin wave, known as a Madden Julian Oscillation (MJO), past just north of Papua New Guinea.
Associated with the Rosby wave component of the MJO were a pair of tropical low-pressure cells located on either side of the Equator that produced a burst of strong westerly winds that dramatically reduced the strength of the West Pacific trade winds a few days later.

The figure below displays the time-longitude plots for 850 hPa westerly wind anomalies covering this period of time. It clearly shows the Aug-Sep and Oct-Nov MJO events that "kill" the West Pacific trade winds around September 17th and November 10th.

If this pattern repeats itself, then we should expect the strength of West Pacific Trade winds to die down around January 4th, 2020. It will be interesting to see if this is enough to tip the Pacific in its EL Nino mode or will it require a couple more of these (lunar-driven) events.

Thursday, December 12, 2019

The Lunar Alignment Density Index and the Upcoming 2020 El Nino Event

There have been five major El Nino events between 1996 and 2019. These events occurred in the years: 1997-98, 2002-03, 2006-07, 2009-10, and 2015-16.

These events occur when the Equatorial Southern Oscillation Index (Eq. SOI) is > 0.0 for an extended period of time as shown by the red curve in the first of two figures displayed below.

N.B. For a decription of the Eq. SOI go to:

Wilson and Sidorenkov (2020) have developed a preliminary Lunar Alignment Density Index (LADI) that shows that there are increases in the frequency of periods of close alignment (< 0.6 days) between two lunar cycles, that precede each of these major El Nino events. See the areas in dark blue that are highlighted in the following graph.

The exact nature of the LADI cannot be discussed at this point because it is being submitted for publication in the peer-reviewed literature. Suffice it to say, that index incorporates two distinct lunar cycles that we believe are responsible for the generation of Equatorial Rosby and Kelvin waves.

Reference Eq. SOI:

What the LADI tells us is that if our hypothesis connecting the two lunar cycles with the generation of Equatorial Rossby and Kelvin Waves is correct, then the should be a major El Nino event sometime in the coming year (i.e. 2020).

It is important to note, however, that the prediction of a 2020 El Nino event is subject to the caveat that we are approaching a period where the 11.2-year (solar-driven) cycle in the strength of the (Equatorial) West Pacific trade winds reaches a maximum sometime in 2021-22 (see the graph below). This could tip the Pacific Ocean towards a La Nina event just after the 2020 El Nino event (i.e. possibly by the 2020-21 southern-hemisphere summer.)