Representativeness requires an appropriate match between the scale of the phenomenon being studied and the spatial and temporal coverage of the sensor. It also requires collecting a sufficient and appropriately distributed number of measurements covering that scale. For example, a regularly spaced set of measurements over one minute, where the wind speed is about 10 m/s, is representative of an upstream fetch of 600 meters.
The number and spacing of sensors and the sampling frequency required to give representativeness depends on the scale of the phenomenon being studied. An example of a measurand having particularly high temporal and spatial variability is rainfall.
In terms of representativeness, field research presents particular challenges. For example, consider the deployment of mobile instrument platforms needed to characterize the mesoscale features studied during the Plains Elevated Convection At Night (PECAN) campaign. In this study, an array of fixed and mobiles sites, some with single instruments and others with an assortment of instruments, were used to establish a representative footprint (shown in the map) covering features of interest to the project.
What factors need to be considered to determine representativeness?
All of the above must be considered to determine site representativeness.