The Lunar Tidal Model - Part 3

Please read:

The Lunar Tidal Model - Part 1
http://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-1.html

The Lunar Tidal Model - Part 2
https://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-2.html

The following question was presented in Part 2:

"Are the equatorial Rossby waves, that are seen trailing the active phase of an MJO, being generated at the times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day], either at a tidal minimum (i.e. at a lunar standstill) or at a tidal maximum (i.e. at a lunar equatorial crossing)?"

As a reminder, figure 1 [i.e. figure 2 in Part 2] below shows a schematic diagram of the relative (lunar-induced) tidal height on the Earth's equator, when measurements are taken at a fixed point in the 24.8-hour lunar tidal day. [Again, note that this is only a rough schematic diagram that is designed to give an idealistic view of how the tides would vary over a lunar tropical month. No attempt is made to allow for the varying distance of the Moon from the Earth and the actual values shown in the graph are only intended to create a qualitative impression of what is happening.]

Figure 1 starts out with the sub-lunar point at its northernmost latitude and it shows that there are four times during a tropical month where there is an ebb in the equatorial tidal height [when measured at a fixed point in the lunar day]. Each one corresponds to a lunar equatorial crossing or a lunar standstill.

Figure 1

The following refers to a specific case of an MJO event that occurred just recently between December 2nd of 2018 and January 6th of 2019. Figure 2 below shows lunar-induced changes in the the relative angular velocity (Delta Omega/Omega) of the Earth over this time period [Sidorenkov 2009]. This figure is used to identify six dates during this MJO event that are at, or within one day of, one of the times of either a lunar equatorial crossing or a lunar standstill. These dates are close to times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day].

  

Figure 2

The following set of six figures show surface wind patterns (1000 hPa level) in the Earth's atmosphere on the dates that are highlighted in figure 2 (https://earth.nullschool.net/). The wind maps cover the equatorial regions of the Indian and Western Pacific oceans. Each map shows the nominal location of the active phase of the MJO on the designated date [Note: This is only a rough estimate that is based upon the geological location of the published MJO phase for that date (Wheeler and Hendon 2004, BOM 2019)]. Additionally, each map shows the location of the Westerly Wind Bursts

(WWBs) and Equatorial Rossby Waves (ERW) associated with each MJO event. All six maps show surface wind conditions for the geological location of the active phase of the MJO at a time that corresponds to the local mid-afternoon. 

02/12/2018 - https://earth.nullschool.net/

09/12/2018 - https://earth.nullschool.net/

19/12/2018 - https://earth.nullschool.net/

22/12/2018 - https://earth.nullschool.net/

29/12/2018 - https://earth.nullschool.net/

05/01/2019 - https://earth.nullschool.net/

Some important points to note:

a) The MJO event stalls in phase 5 (located just south of the Philippines) between the December 15th, 2018 and January 1st, 2019. This could indicate that the propagation of this MJO wave was impeded by:

• its passage through the Maritime Province (i.e. the Indonesian Archipelago)
• its temporary linkage to the monsoon trough across the northern part of Australia.

b) The twin low-pressure cells that form on each side of the equator are a manifestation of the westerly propagating Equatorial Rossby Wave (ERW). These low-pressure cells only start forming a day or so before the dates of the six surface wind maps and so they appear to be associated with the ebb of the lunar-induced tides along the Earth's equator roughly once every 6.8 days.

c) The reemergence of a strong MJO event in phase region 7, following its passage through the Maritime Province, could be the result of the decoupling between the slower moving MJO wave and a much faster move Kelvin Wave that usually takes place in this region of the western Pacific Ocean.

Conclusion:

Careful analysis of these six maps supports the contention that the equatorial Rossby waves, that are seen trailing the active phase of an MJO, are being generated at the times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day], i.e. either at a tidal minimum (at a lunar standstill) or at a tidal maximum at the Earth's equator (at a lunar equatorial crossing).

N.B. This blog post is not a definite proof of the stated conclusion, however, it does provide evidence for further investigation of the proposed hypothesis.   

References:

Sidorenkov, N.S., 2009: The Interaction Between Earth’s Rotation and Geophysical Processes, Weinheim: Wiley.

https://earth.nullschool.net/ last accessed 07/02/2019

Wheeler, M. C., and H. H. Hendon, 2004: An all-season real-time multivariate MJO index:

Development of an index for monitoring and prediction. Mon. Wea. Rev., 132, 1917-1932.

Australian Bureau of Meteorology (BOM), 2019: http://www.bom.gov.au/climate/mjo/  last accessed 06/02/2019.