Overlay Mapper Backgrounds
Layer Notes - CQ Zones
The CQ Zone background layer shows how North America has been divided into regions by CQ magazine. This zone system is the most popular one amongst Radio Amateurs, and is used in many contests and operating awards.
Layer Notes - ITU Zones
The ITU Zone background layer shows the various regions that divide North America from the total of 90. These zones can also referred to as 'IARU' zones. This zone system is not as popular as the more common CQ Zone system, but is still used in a number of contests and operating awards.
The many published definitions of each zone can be contradictory, and some of the lists have definite discrepancies. They were supposedly sorted out earlier, when a proposal was put to the IARU Region 1 Conference in 1996 by the HF Committee of RSGB that common boundaries be identified and a common list be drawn up. This was then tabled at Lillehammer in 1999, then in Darwin, Region III in 2000 and then at the Region II meeting in 2001. At each of these meetings the paper (as originally drafted by John Forward, G3HTA, and based on the ITU CIRAF regions used in the broadcasting service) was accepted for use by the amateur radio service and approved by all Regions of IARU. However, even today, the lists given by a number of major IARU member societies contradict each other, so you should be aware that conflicts might be noticed. The information currently on each of the ITU Zone overlays is however believed to be the most accurate of any map presently available, and if any changes become necessary, the updated overlays will be made available for download. For more information, see the Updates page.
Note that any list of regions is normally composed of the countries represented, so therefore any lines across sea or ocean are generally representational, and should not be regarded as strictly definitive.
Layer Notes - Time Zones
As with other zone overlays, the Time Zones use different colors on land, and lines in ocean or sea areas, to differentiate between them. They are identified by numbers within or adjacent to each zone. The base-point in any map of time-zones is Longitude 000degree, a line running from the North Pole to the South Pole, and passing through the London borough of Greenwich, which has given its name to Greenwich Mean Time, more commonly known these days as 'UTC'. Time zones are all marked with a number relative to the zone at Greenwich, and start either with a '-', indicating that the hour-value is subtracted from the current time at Greenwich, or with a '+', or with no preceding sign, indicating that the hour-value is added to the current time at Greenwich.
Two examples of this might be helpful: Brazil, is in the '-3' time-zone. If the time in London is 9am, you would subtract the 3 to give a current time of 6am in Brazil. China is in the '+8' time-zone. If the time in London is 9am, you would add the 8 to give a current time of 5pm in China.
Note that no account is taken of any shift caused by Summer Time, when the clocks are moved 1 hour forward in the spring, and 1 hour back in the Autumn. The adoption of Summer Time is neither universal or comprehensively coordinated.
Although the general position of time zones is widely acknowledged, when the scale of a map is increased to the level present in some of the overlays here, there can be some dispute as to the exact border of each zone. I have taken my data from the normal standard sources, though as with other data, no claim is made to the accuracy or even the existence of any time-zone boundary on these maps.
Layer Notes - ARRL Sections
The American Radio Relay League (ARRL) divides the USA into 15 Divisions and 71 Sections.
The Radio Amateurs of Canada (RAC) divide their territories into 13 sections, and use a two or three-letter province code as their section abbreviation.
The sections are used as an exchange in a number of contests, including the popular Field Day and Sweepstakes.
Many of the USA sections consist of entire states; some states have more than one section. Each division is headed by a director. Each section is headed by a section manager.
The different sections have a background layer as well as a foreground overlay in the North American Overlay Mapper. The background layer consists of colored areas and borders that define each section area; the foreground overlay consists of colored borders and text. The reason for this separation is so that the section borders and text can be overlayed and compared with other data; i.e. to see where the section borders are on the relief map, or to see which counties fall within which section area.
Layer Notes - States and Provinces
The United States of America (USA) is divided into 50 states + the District of Columbia (DC) which is not a state. Canada is divided into 13 provinces. Mexico is divided into 32 states, though not all are shown in the North American Overlay Mapper, which has a southern border of 24 degrees North.
The USA states and Canadian provinces use a two-letter code for an abbreviation, though the Northwest Territories can also use the three-letter 'NWT'. Mexican states all use a three-letter code.
The state/province names and abbreviations are used as an exchange in a number of contests, mainly the international events.
The ARRL does not use the states as region-identifiers in its organization due to amateur population density; instead it divides the USA into 15 Divisions and 71 Sections. For more details, see the 'ARRL Section' page here.
The different states and provinces have a background layer as well as a foreground overlay in the North American Overlay Mapper. The background layer consists of colored areas and borders that define each state or province area; the foreground overlay consists of colored borders and text. The reason for this separation is so that the state/province borders and text can be overlayed and compared with other data; i.e. to see where the state/province borders are on the relief map, or to see which sections fall within which state area.
Layer Notes - Counties and Municipal Regions
The primary political divisions of most States in the United States of America are termed "counties". There are currently 3077 counties as defined under the requirements of CQ Magazine and the Mobile Amateur Radio Awards Club for credit towards their respective awards, though this has changed in the past and may change again in the future.
In Louisiana, divisions are known as "parishes", a name that derives from the influence of the church at their inception.The District of Columbia has no primary divisions or county government, so is not classed as a county. For County Hunting purposes, the DC area counts as either Montgomery or Prince George's in Maryland. County Hunters use the 4 Judicial Districts of Alaska as counties, rather than the 15 Boroughs, 11 Geographic Census Divisions, and one Municipality that divide the state. The five major islands of Hawaii, are also considered counties.
In certain states, there are cities that are independent of any county organization and thus constitute primary divisions of their states. These cities are known as "independent cities" and are treated as equivalent to counties for statistical purposes. However, for County Hunting purposes, the independent cities are included with their surrounding or associated county.
As of 2020, there are 41 such cities in the United States: Baltimore-Maryland, Carson City-Nevada, St. Louis-Missouri, and 38 cities in Virginia. For County Hunting purposes, the following lists the counties for which Independent Cities can be used:
State City County
Maryland Baltimore Baltimore
Nevada Carson City Douglas, Lyon, Story or Washoe
Missouri St. Louis St. Louis
Virginia Alexandria Arlingtion or Fairfax
Virginia Bristol Washington
Virginia Buena Vista Rockbridge
Virginia Charlottesville Albermarie
Virginia Chesapeake Isle Of Wight
Virginia Colonial Heights Chesterfield or Prince George
Virginia Covington Alleghany
Virginia Danville Pittsylvania
Virginia Emporia Greensville
Virginia Fairfax Fairfax
Virginia Falls Church Fairfax
Virginia Franklin Southampton
Virginia Fredericksburg Spotsylvania
Virginia Galax Caroll or Grayson
Virginia Hampton York
Virginia Harrisonburg Rockingham
Virginia Hopewell Prince George
Virginia Lexington Rockbridge
Virginia Lynchburg Amherst, Bedford or Campbell
Virginia Manassas Prince William
Virginia Manassas Park Prince William
Virginia Martinsville Henry
Virginia New Port News York
Virginia Norfolk Isle Of Wight
Virginia Norton Wise
Virginia Petersburg Chesterfield, Dinwiddie or Prince George
Virginia Poquoson York
Virginia Portsmouth Isle Of Wight
Virginia Radford Montgomery
Virginia Richmond Chesterfield or Henrico
Virginia Roanoke Roanoke
Virginia Salem Roanoke
Virginia Staunton Augusta
Virginia Suffolk Isle Of Wight Or Southampton
Virginia Virginia Beach Isle Of Wight
Virginia Waynesboro Augusta
Virginia Williamsburg James City
Virginia Winchester Frederick
Independent Cities have been left in the county lists with the Table Viewer, but can be differentiated from counties by not having a county abbreviation.
Canadian Provinces do not have a standardized county system like most of the US does. Some provinces have counties similar to those in the USA, but even those are subject to change. Ontario for instance has counties, but many of them are being merged into Municipal Regions. Likewise, Mexico does not have counties, but uses Municipal Regions at this level of government. For this reason, the North American Overlay Mapper uses Municipal Regions as the county information for maps covering Canada and Mexico.
The USA counties also have a Radio Amateur-assigned five-letter code for an abbreviation. Whilst not in common use, this code is utilized for some contests and county QSO-parties. A full list of these codes can be seen in the county lists with the Table Viewer.
The different counties and municipal regions have a background layer as well as a foreground overlay in the North American Overlay Mapper. The background layer consists of colored areas and borders that define each county and municipal region area; the foreground overlay consists of colored borders and text. The reason for this separation is so that the county/municipal region borders and text can be overlayed and compared with other data; i.e. to see where the county/municipal regions are on the relief map, or to see which county/municipal regions fall within which state or province area.
Layer Notes - Earth's City Lights
The background layer of Earth's City Lights is used with only two maps: Overview East and Overview West. This composite satellite photograph of North America clearly shows the actual light radiated from towns and cities all over the continent.
The image was created with data from the US Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Originally designed to view clouds by moonlight, the OLS is also used to map the locations of permanent lights on the Earth's surface. The lights, derived from 9 months of observations by the Defense Meteorological Satellite Program, have been superimposed on a darkened land surface map.
The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. Cities tend to grow along coastlines and transportation networks. Even without the underlying map, the outlines of the continent would still be visible. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. Even more than 100 years after the invention of the electric light, some regions remain thinly populated and dark. Deserts in the United States are poorly lit (except along the coast), as are the boreal forests of Canada.
A variety of different sized images covering the whole world can be downloaded from this website:
http://visibleearth.nasa.gov/cgi-bin/viewrecord?5826
Credits:
Data courtesy Marc Imhoff of NASA GSFC and Christopher Elvidge of NOAA NGDC.
Image by Craig Mayhew and Robert Simmon, NASA GSFC.
Satellite: DMSP
Data Source: DMSP OLS
Layer Notes - Satellite Photograph
The background layer 'Photo' is extracted from NASA's 656MB 43200x21600 pixel tiff image 'land_shallow_topo'; its scale of 120 pixels per degree determined the choice of scale for NAOMI. This spectacular 'Blue Marble' image, a composite of Land Surface, Shallow Water, and Shaded Topography, is the most detailed true-color image of the entire Earth to date. Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations into a seamless, true-color mosaic of every square kilometer of our planet.
Much of the information contained in this image came from a single remote-sensing device-NASA's Moderate Resolution Imaging Spectroradiometer, or MODIS. Flying over 700 km above the Earth on board the Terra satellite, MODIS provides an integrated tool for observing a variety of terrestrial, oceanic, and atmospheric features of the Earth.
The land and coastal ocean portions of these images are based on surface observations collected from June through September 2001 and combined, or composite, every eight days to compensate for clouds that might block the sensor's view of the surface on any single day. Two different types of ocean data were used in these images: shallow water true color data, and global ocean color (or chlorophyll) data.
Topographic shading is based on the GTOPO 30 elevation dataset compiled by the U.S. Geological Survey's EROS Data Center. MODIS observations of polar sea ice were combined with observations of Antarctica made by the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer sensor, or AVHRR.
A variety of different sized images covering the whole world can be downloaded from this website:
http://visibleearth.nasa.gov/cgi-bin/viewrecord?11656
Credits:
NASA Goddard Space Flight Center Image by Reto Stöckli (land surface, shallow water).
Enhancements by Robert Simmon (ocean color, compositing).
Data and technical support: MODIS Land Group; MODIS Science Data Support Team; MODIS Atmosphere Group; MODIS Ocean Group
Additional data: USGS EROS Data Center (topography); USGS Terrestrial Remote Sensing Flagstaff Field Center (Antarctica).
Satellite: Terra
Sensor: MODIS
Layer Notes - Colored Relief Map
The images used for the relief map background layer were generated as a color relief map with data extracted from the GTOPO30 dataset, and then combined with a black and white shaded relief image to provide a suitable level of depth.
GTOPO30 is a global digital elevation model (DEM) resulting from a collaborative effort led by the staff at the U.S. Geological Survey's EROS Data Center in Sioux Falls, South Dakota. Elevations in GTOPO30 have a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was developed from several raster and vector sources of topographic information to meet the needs of the geospatial data user community for regional and continental scale topographic data. The GTOPO30 dataset is divided into 33 tile datasets, available for download at the GTOPO website.
The colors chosen were designed to give a clear idea of elevation changes. A key to the colors used, and the elevation values that they represent, can be seen above. The degree of shading used also depends on elevation - these colors can also be seen above. All values are in metres.