calculate_param {bioRad}

Calculate a new scan parameter

Description

Calculate a new parameter (param) for a scan (scan) or polar volume (pvol)

Usage

calculate_param(x, ...)

## S3 method for class 'pvol'
calculate_param(x, ...)

## S3 method for class 'ppi'
calculate_param(x, ...)

## S3 method for class 'scan'
calculate_param(x, ...)

Arguments

x

A pvol or scan object.

...

An expression defining the new scan parameter in terms of existing scan parameters.

Details

Calculates a new scan parameter (param) from a combination of existing scan parameters. Useful for calculating quantities that are defined in terms of other basic radar moments, like linear reflectivity eta, depolarization ratio (Kilambi et al. 2018), or for applying clutter corrections (CCORH) to uncorrected reflectivity moments (TH) as TH + CCORH.

Value

An object of the same class as x, either a pvol or scan.

Methods (by class)

• calculate_param(pvol): Calculate a new parameter (param) for all scans in a polar volume (pvol).

• calculate_param(ppi): Calculate a new parameter (param) for a plan position indicator (ppi).

• calculate_param(scan): Calculate a new parameter (param) for a scan (scan).

References

• Kilambi A, Fabry F, Meunier V (2018) A simple and effective method for separating meteorological from nonmeteorological targets using dual-polarization data. Journal of Atmospheric and Oceanic Technology 35, pp. 1415–1424. doi:10.1175/JTECH-D-17-0175.1

• Kilambi, A., Fabry, F., and Meunier, V., 2018. A simple and effective method for separating meteorological from nonmeteorological targets using dual-polarization data. Journal of Atmospheric and Oceanic Technology, 35, 1415–1424. doi:10.1175/JTECH-D-17-0175.1

See Also

• get_param()

Examples

# Locate and read the polar volume example file
pvolfile <- system.file("extdata", "volume.h5", package = "bioRad")
pvol <- read_pvolfile(pvolfile)

# Calculate linear reflectivity ETA from reflectivity factor DBZH
radar_wavelength <- pvol$attributes$how$wavelength
pvol <- calculate_param(pvol, ETA = dbz_to_eta(DBZH, radar_wavelength))

# Add depolarization ratio (DR) as a scan parameter (see Kilambi 2018)
pvol <- calculate_param(pvol, DR = 10 * log10((ZDR + 1 - 2 * ZDR^0.5 * RHOHV) /
  (ZDR + 1 + 2 * ZDR^0.5 * RHOHV)))

# The function also works on scan and ppi objects
calculate_param(example_scan, DR = 10 * log10((ZDR + 1 - 2 * ZDR^0.5 * RHOHV) /
  (ZDR + 1 + 2 * ZDR^0.5 * RHOHV)))

# it also works for ppis
ppi <- project_as_ppi(example_scan)
calculate_param(ppi, exp(DBZH))