For surface based observations, point measurements should be representative of several km2. Specifications differ with application and sometimes with existing observational capability. For FPAR a 30 km resolution is specified as a requirement for terrestrial global applications. Scientifically consistent specifications need to be developed. The above Table identifies page numbers in the reference documents used to extract requirements specifications.
Spectral measurements are extremely limited, though needed.
Long wave components are not measured in too many sites and not exchanged. Most agricultural and ecological stations are equipped with shortwave radiometers. There are some problems with maintaining calibration standards and equipment maintenance. Radiation instrumentation intercomparisons and standards are maintained at the International Radiation Center in Davos, Switzerland. Currently, most observed data are not regionally or internationally exchanged, and in many cases, national archiving procedures are also deficient.