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In locations where a site is presently located, this information should be present with the required
accuracy.
Global Positioning System (GPS) technology can provide the site location to within 30 m without
correction and to better than 5 m with corrected systems. Elevation can also be accurately
determined from GPS. For a new site, this technology may be the easiest and most accurate
means of determining its location.
3.1.4 General site description for the Archive
A second aspect of describing the site location is a general description of the surrounding area.
The Technical Plan for BSRN Data Management (TPBDM), Version 2.1, defines two fields for the
description of each site. The first field is surface type, while the second field is topography type.
These fields are further described in Tables 4.14 and 4.11, respectively, of the TPBDM and are
included as elements in logical record four of the station-to-archive file format. The tables are
reproduced below as Table 3.1 and Table 3.2 for convenience. The form at for each descriptor is
I2.
While these tables are useful, they remain limited in describing the site fully because few sites fall
easily into any simple set of categories as described. To aid researchers in understanding the
overall complexity of the area surrounding a station, a more complete description, including
topographic maps and photos of the site and its surroundings, is required.
3.2. BSRN Station Information Document
While the Archive information provides a brief description of the site and the site survey provides
inform ation on obstructions to the incoming radiative fluxes, if any, a m ore thorough description is
necessary for data users. Individuals involved in the determination of climate change over time or
the validation of satellite algorithms require detailed information about the site surroundings to
determine the quality of the data for their specific needs. For example, individuals studying climate
change require not only a knowledge of the general topography, but also details of city growth,
changes in land use, farming techniques if in an agricultural area or flight patterns and frequency if
near an airport over the tim e period of the measurements. Sim ilarly, those using the data to obtain
vicarious calibrations of satellite-borne instruments require similar knowledge to determine how
representative the site is with respect to its surroundings. To provide this information, a more
complete site description is required. The document, as described, has been modelled after a
similar one designed for the Commission Internationale de l’Éclairage (CIE) International Daylight
Measurement Programme.
Data in relation topography type
Value Topographic Feature Population Density
1 flat urban
2 flat rural
3 hilly urban
4 hilly rural
5 mountain top urban
6 mountain top rural
7 mountain valley urban
8 mountain valley rural
Table 3.1. Topography types used in archive site identification.
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