W hile the Archive inform ation provides a brief description of the site and the site survey provides inform ation on obstructions to the incom ing radiative fluxes, if any, a m ore thorough description is necessary for data users. Individuals involved in the determ ination of clim ate change over tim e or the validation of satellite algorithm s require detailed inform ation about the site surroundings to determ ine the quality of the data for their specific needs. For exam ple, individuals studying clim ate change require not only a knowledge of the general topography, but also details of city growth, changes in land use, farm ing techniques if in an agricultural area or flight patterns and frequency if near an airport over the tim e period of the m easurem ents. Sim ilarly, those using the data to obtain vicarious calibrations of satellite-borne instrum ents require sim ilar knowledge to determ ine how representative the site is with respect to its surroundings. To provide this inform ation, a m ore com plete site description is required. The docum ent, as described, has been m odelled after a sim ilar one designed for the Com m ission Internationale de l’Éclairage (C IE) International Daylight Measurem ent Program m e.
Table 3.1. Topography types used in archive site identification.
The description consists of 11 sections broken down into three m ain areas: General Description, Site Description and Station Description; m uch of this inform ation is required for the Archive, but it is set up as an inform ation package for prospective data users. A description of the inform ation required to com plete the package follows. A blank docum ent is included in Annex A.
3.2.1 General Description
(1) Inform ation on whom the scientific authority is for the site. Postal address, telephon e, fax and E-m ail if applicable.
(2) The site’s location: latitude (N positive 0 - 90), longitude (East/W est of Greenwich), Elevation above MSL, Local Tim e from GMT, Station Topography and Station Surface Type from the archive, and the date of the first data subm itted to the archive.
(3) Topographic m ap showing the land within a 15 km radius. A topographic m ap with a scale of approxim ately 1:250000 provides the appropriate resolution. This gives users a sense of the hom ogeneity of the surrounding areas.
3.2.2 Site Description
(4) Site Surroundings: a written description indicating population centres, population density. W hen the station is within a large city, the following inform ation should be added to the description: whether the city is growing, stagnant or declining in population. Major sources of pollution. Large bodies of water or significant local topographic effects should be noted. If the site is located at an educational institution or on the top of a building.
(5) Clim ate characteristics: the general clim ate type (e.g., m aritim e, polar, etc.), clim atic norm als (m in/m ean/m ax sum m er/winter tem peratures, m ean rainfall etc.), significant clim atic events (e.g., m onsoons, hurricanes, tornadoes)
(6) A m ap of the local area around the station (approxim ately a 1 to 2 km radius). A recent topographic m ap or photom ap with a scale of 1:50000 provides the necessary resolution.
3.2.3 Station Description
(7) A list of all the radiation fluxes being m easured routinely at the station and the types of instrum ents being used. The type of data acquisition system (s) being used, the sam pling rates of the data acquisition system and the outputs that are being archived. Inform ation on the tracking and shading system s that are being used in obtaining the m easurem ents is also required.
(8) A station m ap: a detailed m ap indicating the location of the individual sensors in relation with each other. This m ap is prim arily for the radiation instrum entation locations and need not include the location of the m eteorological station or upper air station. Such inform ation would be on the station m ap if the distances were greater than approxim ately 20 m .
(9) A horizon view of the global radiation sensor indicating the m ajor obstructions. This would be a figure utilizing the data supplied to the Archive running from North through South to North in a clockwise direction.
(10) Com m ents on the site. For exam ple, com m ents would include the instrum entation and data acquisition system s that are used for the m eteorological variables. If another individual is the responsible contact for the m eteorological portion of the site, the nam e and address would be included in these com m ents. A brief description of the m ethod and frequency of the calibration of the sensors would be included in this set of com m ents. If a particular set of research m easurem ents were being m ade at the site, this should be noted and the nam e and address of the appropriate contact given. This section can be used by the site m anager to advertise anything that m akes the particular site special.
Data in relation surface type
Value Major Surface Type Descriptor
1 glacier accum ulation area
2 glacier ablation area
3 iceshelf
-4 sea ice
-5 water river
6 water ocean
7 water ocean
8 desert rock
9 desert sand
10 desert gravel
11 concrete
-12 asphalt
-13 cultivated
-14 tundra
-15 grass
-16 shrub
-17 forest evergreen
18 forest deciduous
19 forest m ixed
20 rock
-21 sand
-Table 3.2. Surface types used in archive site identification.
(11) Photographs of the station and its surrounds. Up to 4 photographs with appropriate com m ents should be provided. These can convey useful inform ation concerning the instrum ent set-up and the surrounding horizon if there are significant obstructions. For exam ple, if a tower is found on the site, a photograph m ay be appropriate to show where the instrum ents are located, or four pictures of the cardinal points of the com pass from the central instrum ent with a wide-angle cam era. In a m anner sim ilar to the com m en ts section above, the photographs are to convey inform ation about the station to the data users.
The BSRN Station Description docum ent should be updated regularly. If significant changes occur in the instrum entation, the horizon or the ancillary m easurem ents, corrections should be m ade im m ediately. In a m anner sim ilar to the horizon survey, the site description should be updated every five years.