Global Positioning (GPS) and Local Commercial Noon (LCN)

Global Positioning would be impossible without very accurate timekeeping, but having determined an approximate position, the timekeeping precision requirements vanish, and local "real time" requirements come to the fore. Local positioning can be maintained address book style, that is, with Place Nicknames linked to a sparse row-wise list of identifiers and data. The common storage for this type of data is LDAP rather than a RDBM, although there are some Marshalling issues which need to be addressed first.

An XML example is:

            [North America].[United States].[California].[San Francisco County].[San Francisco city]
         <dct:alternative>San Francisco, CA</dct:alternative>

Data Sources

The identifier is a quoted list of names read from left to right. The Library of Congress has assigned URI's down to the State level. The FIPS numeric codes are complete to the County level, but unenlightening for semantic work. The Census Gazetteer uses text/type descriptors with supplies (interpolated) latitude and longitude values. The rightmost term is related to the Nickname. If the rightmost term is changed, the node changes. For example, the IATA Code for San Fransisco International Airport is: SFO. The dct:spatial data changes, the dct:temporal data may change, but in any event the Nickname should change.
San Francisco, CA ... [North America].[United States].[California].[San Francisco County].[San Francisco city]
San Francisco International Airport CA ... [North America].[United States].[California].[San Francisco County].[SFO]
The Place Nickname. The City of San Francisco is also the County Seat of San Francisco County, hence the Nickname "San Francisco, CA". The Nickname is user supplied, but arcs to the rightmost label of the identifier [San Francisco city]. The National Weather Service uses 13 Miles WSW Buoy 26 CA as a Nickname. In fact the spot designated as [San Francisco city] by the Census Gazetteer is well offshore in the Pacific Ocean.
Latitude, Longitude and Elevation. Latitude and Longitude can be delivered by GPS, Authority or approximated by pointing a mouse at a map. Elevation is often idealized. This is a particular use case where UP is interesting and DOWN is not not very interesting to the user. There are significant classes of users for which this case is insufficient, e.g. Weather Forecasts for pilots, nonetheless there are a large number of users for this case. To be sure, Elevation is often very important to the science and computation behind the data. This has no bearing on a ground bound user. Humans do not fly well under their own power.
Universal Coordinated Time Offset (UTC) and Local Commercial Noon. Time Zones are well known, but unevenly distributed across the Longitudinal Grid. There are but a few US Counties with multiple Time Zones. There is also a County Warning Area (CWA) grid mapped, with Time Zone data. The County Warning Area can be used as a rightmost identifier (see below). Local Commercial Noon, discussed at length below, is an idealized value like Elevation.
MTR San Francisco CWA CA ... [North America].[United States].[California].[San Francisco County].[MTR]

What is Local Commercial Noon ?

Day by day activity schedules are persistent over time. Clocks are always adjusted at or around Midnight, for minimum disruption of human activity. Yet the day-to-day variability of Solar Noon makes it unsuitable for use with persistent activity schedules. Choosing a fixed Noon, rather than a fixed Midnight enables schedules to be centered around an activity period midpoint, rather than a period of inactivity.

Local Commercial Noon (LCN) is equal to Solar Noon on the Winter Solstice rounded to the nearest 15 minutes.

Local Commercial Noon, then, is just the other side of Midnight. Periods of work (production), leisure (consumption) and rest revolve around this idealized noon, and forecasts of various kinds can be synchronized. Persistent time schedules, centered at 12:00:00 PM can easily be overlay-ed since the offset will be constant for an entire year. Weather reports, for instance, are time-shifted forward by a "constant" amount (Today (Day or Current) and Tonight (Overnight)) as if the last sunrise was the starting point. Some Religious calendars time-shift backwards to the previous sunset, but again, the "constant" amount presents no problem for synchronization.

Although the Winter Solstice is different in the Northern Hemisphere (ca. Dec. 22) and the Southern Hemisphere (ca. Jun. 21), Daylight Saving Time is never in effect unless permanent. This is an aid to calculation since only a very few Countries have permanent Summer Time or Daylight Saving Time. The Russian Federation, and perhaps Belarus are on permanent Summer Time. Much more common are the locations within about 10° of the equator which have no need for Daylight Saving Time.

Solar Noon on the Winter Solstice is calculated to the second, then rounded to the quarter hour. The San Francisco examples have distinct values, but they all round to 12:15:00 PM.

San Francisco, CA
[North America].[United States].[California].[San Francisco County].[San Francisco city]
San Francisco city Weather, CA
[North America].[United States].[California].[San Francisco County].[13 Miles WSW Buoy 26 CA]
San Francisco International Airport CA
[North America].[United States].[California].[San Francisco County].[SFO]
MTR San Francisco CWA CA
[North America].[United States].[California].[San Francisco County].[MTR]
Downtown San Francisco Weather
[North America].[United States].[California].[San Francisco County].[SAN FRANCISCO DOWNTOWN (SFOC1)]
111th CA 12th Congressional District
[North America].[United States].[California].[San Francisco County].[FIPS0612]
The Place Across the Bay
[North America].[United States].[California].[Alameda County].[Oakland city]
12:07:30 (12:00:00, just, rounded down)

Jurisdiction and Local Commercial Noon

The last two cases above are interesting. The GPS Coordinates are from the Census Gazetteer. They relate "San Francisco" with the "California 12th Congressional District" by virtue of having the same LCN and disassociate "Oakland city" from "San Francisco" on the same basis.

The GPS Coordinates of places close to each other form a natural Jurisdiction. A system of services for a Municipality can be grouped by Local Commercial Noon, even though any individual coordinate set appears to be random, with a random label. This convergence goes by the name Monte Carlo Quadrature, or Monte Carlo Integration in mathematics. The principle is painfully simple, to estimate the area of a region, draw a box around it and throw darts at the map. The area is the ratio of the number of darts landing inside the region to the number of darts landing inside the box. Irregular regions may require more darts or a bigger box, but the convergence remains.

The value of LCN is a simple inside/outside test for the natural Jurisdiction, and the rounding of LCN increases or decreases the size of the natural Jurisdiction. For Federal Legislative purposes, "Gerrymandering" an individual region has no effect on the aggregate natural Jurisdiction. Imagine throwing darts at a square jig-saw puzzle with numbered pieces, the aggregate area remains the same if the puzzle is assembled or not. The same can be said for the Law and Court Systems with "Supreme" Courts.

This system tracts the sphere of influence (natural Jurisdiction) of Municipalities and Communities, not people, or individual members. It is thereby very resistant to the "Mosaic Effect" on personal privacy. The only downside seems to be that, if classifying people by Latitude is Junk Anthropology then classifying people by Longitude (Time Zone) is conspicuously Junk Anthropology.

Rounding Time in javascript text version

Rounding time is an easy task for a human, but it is unlike rounding numbers.

Solar Noon: Nearest 1|5|10|15|20|30 minutes: (rounds down)
Local Commercial Noon:

Civil Twilight

At the Solar Noon direct radiation is at a maximum. Apparent sunrise and sunset take into account refraction - the point at which direct radiation vanishes, but there are also periods of twilight, light but no heat, where reflection off clouds, etc. predominates. The earth is never completely dark of course, there are starlight and moonlight.

The data is best tabulated as a collection on a yearly basis. LCN is a special value (about Dec. 22 in the Northern Hemisphere, and Jun. 21 in the Southern Hemisphere.


          <poi:dayAtPointOfInterest poi:id="[North America].[United States].[California].[San Francisco County].[San Francisco city]">
             <poi:dayOfYear rdfs:label="DOY">356</poi:dayOfYear>
             <poi:calendarDate rdfs:label="Date">Dec 22, 2011</poi:calendarDate>
             <poi:summerTime rdfs:label="DST">0</poi:summerTime>
             <poi:startCivilTwilight rdfs:label="Civil Twilight Start (hh:mm:ss)">06:54:50</poi:startCivilTwilight>
             <poi:solarNoon rdfs:label="Solar Noon (hh:mm:ss)">12:10:43</poi:solarNoon>
             <poi:endCivilTwilight rdfs:label="Civil Twilight End (hh:mm:ss)">17:26:36</poi:endCivilTwilight>