Lack of reference levels, therefore it is unknown if trends in environmental change are strong or weak.

It is measured in decibels (dB) above a standard reference level.

Relative terms measure the density against a reference level, which is determined by dominant tree species, the plant community, and site index.

Such sensors can track these low settings over time and recalibrate themselves based on the reference levels.

A more common means of specifying a reference level is relative to a full-scale signal.

Negative number does not necessarily mean position below reference level.

In other media, such as underwater, a reference level of 1 Pa is used.

If too many such measurements occur then the current measurement is rejected and the reference levels recalculated.

As a result, the agreed goals and reference levels were included in the wording of the key guidelines.

Altitude, the height or elevation of a point or object above a given reference level.