The sum of the instrumental and representativeness error covariances, E+F, is often written
as a single observational error covariance R. The above derivation shows that it is composed
of two parts, E which is a function of the instrument characteristics, and F which is a
function of the model resolution. For instance, for a wind observation from a radiosonde,
the errors in tracking the balloon might lead to an instrumental error of about 1ms-1. The
error of representativeness due to trying to predict such a wind from a model with horizontal
grid-length 200km would be about 3ms-1, and a grid-length on 20km would reduce the error
of representativeness to about 1ms-1.