Spatial consistency test
The SCT compares each observations to what is expected given the other observations in the nearby area. If the deviation is large, the observation is removed.
When a given observation is being processed, the outer_radius [m] defines which other observations will be used to determine if the observation should be flagged or not. This can be computationally expensive, if a new circle of observation is used when processing the next observation. To save time, the calculations used for one observation can be reused for all other observations within the inner_radius [m].
The test will only be performed if there are at least num_min observations inside the outer circle. Also,m to reduce computation time, only the nearest num_max observations will be used in the outer circle, even if there are more available observations. The SCT inverts a matrix with the same dimensions as the number of available observations, therefore preventing really large matrices in observation dense areas significantly lowers computation times.
The thresholds for determining if an observation is removed is set by pos and neg. pos sets the number of standard deviations above the expected value a given observation is allowed before being flagged. Similarly, neg is used for negative deviations. Different deviations for positive and negative are useful for sun-exposed temperature sensors in cold inversion conditions, where large negative deviations are more likely to be valid than positive ones.
num_iterations specifies how many sweeps of all observations will be performed. Observations removed in earlier iterations will not be used in the calculations in later iterations.
