OutlierFilterMinMaxRSL: Function to apply filter to remove outliers in path-averaged...

In overeem11/RAINLINK: Retrieval algorithm for rainfall mapping from microwave links in a cellular communication network.

Function to apply filter to remove outliers in path-averaged microwave link attenuations.

Description

Function to apply filter to remove outliers in link-based rainfall estimates. Malfunctioning link antennas can cause outliers in rainfall retrievals (especially for daily accumulations). These outliers can be removed by using a filter that is based on the assumption that rainfall is correlated in space. The filter discards a time interval of a link for which the cumulative difference between its specific attenuation and that of the surrounding links over the previous 24 h (including the present time interval), F, becomes lower than a threshold value in dB h km^{-1}.

Works for a sampling strategy where minimum and maximum received signal powers are provided, and the transmitted power levels are constant.

The outlier filter has been extensively tested on minimum received signal powers, i.e. for a sampling strategy where minimum and maximum received signal powers are provided, and the transmitted power levels are constant. This function can also be applied in case of other sampling strategies, because it does not explicitly require minimum and maximum received signal powers. It just applies the selection on all rows in a data frame. Whether the outlier filter will give good results when applied to link data obtained from other sampling strategies would need to be tested. Hence, ”MinMaxRSL” is kept in this function name to stress that it has been tested for a sampling strategy where minimum and maximum received powers are provided.

Also works for a sampling strategy where instantaneous transmitted and received signal levels are obtained. In case of instantaneous signal levels, it does not matter whether transmitted power levels vary or are constant. The only requirement is that the input data for RAINLINK needs some preprocessing. See ”ManualRAINLINK.pdf” for instructions.

Also works for a sampling strategy where average transmitted and received signal levels are obtained. In case of average signal levels, it does not matter whether transmitted power levels vary or are constant. The only requirement is that the input data for RAINLINK needs some preprocessing. See ”ManualRAINLINK.pdf” for instructions.

Can only be applied when function WetDryNearbyLinkApMinMaxRSL has been executed.

Usage

OutlierFilterMinMaxRSL(Data, F, FilterThreshold = -32.5)

Arguments

Data	Data frame with microwave link data.
F	Values for filter to remove outliers (dB km^{-1} h).
FilterThreshold	Outlier filter threshold (dB h km^{-1}).

Value

Data frame with microwave link data.

Author(s)

Aart Overeem & Hidde Leijnse

References

”ManualRAINLINK.pdf”

Overeem, A., Leijnse, H., and Uijlenhoet, R., 2016: Retrieval algorithm for rainfall mapping from microwave links in a cellular communication network, Atmospheric Measurement Techniques, 9, 2425-2444, https://doi.org/10.5194/amt-9-2425-2016.

Examples

OutlierFilterMinMaxRSL(Data=DataPreprocessed,F=WetDry$F,FilterThreshold=-32.5)

overeem11/RAINLINK documentation built on July 8, 2023, 5:53 a.m.