Interpolation: Interpolation of link-based path-averaged rainfall estimates.

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

Interpolation of link-based path-averaged rainfall estimates.

Description

Interpolation of link-based path-averaged rainfall estimates. The type of interpolation has to be specified. The following types are available: 1) Inverse distance weighted interpolation on data (subfunction IDW); 2) Ordinary kriging with spherical variogram model. Its parameter values nugget, sill, and range, can be defined by the user; 3) Ordinary kriging with spherical variogram model with climatological parameter values based on a 30-year rain gauge data set. These are computed for the day of year as obtained from the file name, thus taking into account seasonality in spatial rainfall correlation. The subfunction ClimVarParam computes these parameter values.

Ordinary kriging is performed by subfunction OrdinaryKriging. Note that this interpolation algorithm is developed for interpolation of link-based rainfall estimates, which are path averages. The subfunction IntpPathToPoint computes the path-averaged rainfall intensities for unique link paths. And it assigns path-averaged intensity to the point at the middle of the link path.

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

Usage

Interpolation(
  Data,
  idp = 2,
  InputCoorSystem,
  IntpMethod = "OK",
  LocalCartesianCoorSystem,
  nmax = 50,
  NUGGET,
  RANGE,
  RainGrid,
  Rmean,
  SILL,
  TimeZone = "UTC",
  Variogram = "ClimVar",
  OutputDir = NULL
)

Arguments

Data	Data frame with microwave link data.
idp	The inverse distance weighting power.
InputCoorSystem	Define EPSG code for input coordinate system (e.g., 4326L for WGS84 in degrees).
IntpMethod	Interpolation method: Ordinary kriging ("OK") or inverse distance weighted interpolation ("IDW").
LocalCartesianCoorSystem	Define EPSG code for (local) Cartesian coordinate system (meters).
nmax	The number of nearest observations that should be used for a kriging prediction or simulation, where nearest is defined in terms of the space of the spatial locations.
NUGGET	Nugget of spherical variogram model (mm).
RANGE	Range of spherical variogram model (km).
RainGrid	Data frame containing information on the points in space where rainfall needs to be estimated, is assumed to be in the same coordinate system as the link locations (InputCoorSystem).
Rmean	Vector of link-derived rainfall intensities (mm h^{-1}) with length equal to Data.
SILL	Sill of spherical variogram model (mm^2).
TimeZone	Time zone of data (e.g. "UTC").
Variogram	For OK: which variogram to use? Use "ClimVar" for climatological spherical variogram model. Use "Manual" for spherical variogram model with NUGGET, SILL, and RANGE values supplied as function arguments.
OutputDir	If supplied (not NULL), files with resulting interpolated rainfall fields will be written to this directory. If not supplied, the interpolated fields will be returned.

Value

Interpolated field of rainfall intensities (mm h^{-1}).

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

Interpolation(Data=DataPreprocessed,idp=2.0,InputCoorSystem=4326L,
IntpMethod="OK",LocalCartesianCoorSystem=28992,nmax=50,NUGGET=0.37,RANGE=18.7,RainGrid=RainGrid,
Rmean=Rmean,SILL=3.7,TimeZone="UTC",Variogram="ClimVar",OutputDir="RainMapsLinks15min")

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