21SPACEWX Where the plane of the lunar orbit meets the surface of the Earth - a netCDF database

Does Earth have a ring system? If so, does it influence climate?

A ring system is still sought and not quantified at Earth or any of the rocky planets. But this does not rule out existence, since the methods used to find rings seek density contrasts that may be low. Consider that the rocky planets are much rounder than the gas giants, while it is the oblateness of the gas giants, specifically, that flattens their rings. Thus an Earth ring system would be puffy and low-contrast compared to those at Saturn. Consider also that if Earth’s ring system comprises rings in both orientations known elsewhere in the solar system, namely the equator and the plane of our moon's orbit, then the two puffy rings would be mutually tilted at 28 degrees. Consider finally that the orbits of dust particles in a circumterrestrial ring would be unstable, thus a ring could be faint even if permanent, as it would be constantly eroded. In sum, the observational challenge would be to distinguish two faint puffy rings mutually tilted at 28 degrees. Very rarely would they be side-on at the same time.

Yet a faint, puffy, unspectacular ring system could be a driver of weather and climate.

As several authors have discussed, a ring system would shade Earth cyclically. In addition, a ring system could drive climate through the infall of ring dust to the atmosphere. After all, dust orbits would be unstable. Infalling space dust would likely convey charge built up in space by the photoelectric effect. It would also convey mass, momentum and angular momentum through the atmosphere to the surface of the Earth. Such dust could nucleate raindrops. cause lightning, drive winds, and deliver heat bursts to the atmosphere when heavier particles plummeted and burned. Dust might also deliver localized cold from dust particles too light to plummet. Very importantly, the dust would in likelihood be exceedingly jagged in shape due to its evolution from rock to dust via cycles of rotational bursting. An exceedingly jagged PM2.5 dust component ingested to the lungs of people and animals could cause seasonal, regional enhancements of vulnerability to endemic disease.

The climate and health effects of a ring would in likelihood be long-standing patterns of weather and illness. The reason they would likely be long-standing is that there is little exotic dust in space, from which it follows that if there is a circumterrestrial ring then it must be so old that its dust contribution has become incorporated in terrestrial geology.

Yet although long-standing, some of these effects would defy precise prediction. While the effects of a ring in the plane of the equator would occur in phase with the solar year, and thus be predictable at least in the short run, the case would be different for effects of a ring in the plane of the lunar orbit. These would elude prediction when represented in geocentric coordinates and in divisions of the solar year.

What is needed to identify ring effects, if there are any, is to associate the celestial frameworks in which they are regular, to the terrestrial frameworks where weather data is assembled and reported.

To that end, this presentation offers and documents a database projecting the lunar orbit to the Earth's surface. Of all possible celestial frameworks, this great circle is chosen because it would be a favored locus for infall of dust from a ring in the plane of the lunar orbit.

To see its value, consider Figure 1. This presents the projection of the lunar orbit at the moment 1 January 2018 06:00 UTC, overlain with Multi-Source Weighted-Ensemble Precipitation (MSWEP) data from the corresponding timepoint. Figure 1 suggests that there are climate effects along that arc. Still, this is only a suggestion. What is needed is a statistical study.

Access to the database and documentation are in this Jupyter notebook. https://colab.research.google.com/drive/1eLScJ1FmrI8Y3uJMZBXLf82NhsfNf2Xy?usp=sharing. The files are prepared once/3 hours from January 2015 to December 2034.

The presentation will also summarize a few key aspects of the intersection of the lunar orbit with the surface of the Earth. For example, it comprises a great circle that orbits Earth about once/day, tilted about 5 degrees to the ecliptic, crossing the ecliptic at two points that precess around the ecliptic once per 18.6 years. The north-south extent of this great circle is confined to the range 30N to 30S, but within that range the annual extent varies over an 18.3 year cycle. If infalling dust drives rainfall, then its variation in north-south extent may account for some cycles of flood and drought. Of note, the north-south range of this arc is near its widest extent this year. If this extended range is the reason for the northern extension of the monsoon in Pakistan, then we can predict that the extension will last a few years, then contract at a knowable time, then expand again at a knowable time.

A further aspect of this geometry is that the dust in the plane of the lunar orbit would orbit the Earth-Moon barycenter (EMB), not the geocenter. These orbits would approach Earth more closely on the side of Earth where the Moon is down. This suggests that at each timepoint, one side of the arc may be favored over the other to fall into the atmosphere, depending on the position of the Earth-Moon barycenter.

Further, a broad effect due to solar heating that causes bumps in the atmosphere is expected to promote infall in some places more than others, with the special case of a land-sea effect.

Figure 1 Caption:

The plane of the lunar orbit (pale blue) on 1 January 2018 06:00 UTC, plus the precipitation estimates from three-hourly MSWEP at the same time.