WetDryNearbyLinkApMinMaxRSL: Function for classifying wet and dry periods according to the...

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

Function for classifying wet and dry periods according to the nearby link approach. Function also prepares link data for determination of reference signal level and for computing corrected received powers.

Description

The received signal powers often decrease during non-rainy periods, resulting in non-zero rainfall estimates, e.g. caused by reflection of the beam or dew formation on the antennas. To prevent this rainfall overestimation a reliable classification of wet and dry periods is needed. This is also beneficial for determining an appropriate reference signal level, representative for dry weather. In order to define wet and dry periods, we assume that rain is correlated in space, and hence that several links in a given area should experience a decrease in minimum received signal level in the case of rain. A time interval is labeled as wet if at least half of the links in the vicinity (for chosen radius) of the selected link experience such a decrease. This so called nearby link approach is applied in this function. The function also prepares link data for determination of reference signal level and for computing corrected received powers.

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

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.

The time interval does not have to be an integer but should be equidistant. The minimum time interval length in the time series is automatically computed and is employed as the time interval length.

Usage

WetDryNearbyLinkApMinMaxRSL(
  Data,
  InputCoorSystem = InputCoorSystem,
  LocalCartesianCoorSystem = LocalCartesianCoorSystem,
  MinHoursPmin = 6,
  PeriodHoursPmin = 24,
  Radius = 15,
  Step8 = TRUE,
  ThresholdMedian = -1.4,
  ThresholdMedianL = -0.7,
  ThresholdNumberLinks = 3,
  ThresholdWetDry = 2
)

Arguments

Data	Data frame with microwave link data.
InputCoorSystem	Define EPSG code for input coordinate system (e.g., 4326L for WGS84 in degrees).
LocalCartesianCoorSystem	Define EPSG code for (local) Cartesian coordinate system (meters).
MinHoursPmin	Minimum number of hours in the previous PeriodHoursPmin hours needed for computing max(P_{\mbox{min}}) (h).
PeriodHoursPmin	Number of hours that is considered for computation of max(P_{\mbox{min}}) (h).
Radius	Radius in wet-dry classification (km).
Step8	If TRUE step 8 in the wet-dry classification is performed, else it is not executed.
ThresholdMedian	Threshold value (dB).
ThresholdMedianL	Threshold value (dB km^{-1}).
ThresholdNumberLinks	Only use data if number of available (surrounding) links is at least larger than this threshold for the time interval under consideration. The selected link is also counted.

Value

Data frame: Should interval be considered dry for reference level. determination? (0 = wet; 1 = dry)

Values F for filter to remove outliers (dB km^{-1} h)

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

WetDryNearbyLinkApMinMaxRSL(Data=DataPreprocessed,InputCoorSystem=4326L,
LocalCartesianCoorSystem=28992, MinHoursPmin=6,PeriodHoursPmin=24,Radius=15,
Step8=TRUE,ThresholdMedian=-1.4, ThresholdMedianL=-0.7,ThresholdNumberLinks=3,
ThresholdWetDry=2)

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