IceCast (version 2.1.0)

get_region: Get polygons corresponding to regions

Description

Takes in a matrix and returns a SpatialPolygon object representing regions fitting some criteria. Typically these regions are either where the sea ice concentration is above a certain level or where there is land.

Usage

get_region(dat, dat_type, level = NULL, my_land_mat = land_mat,
  my_all_regions = all_regions, use_all = FALSE, land_ind = FALSE,
  xmn = -3850, xmx = 3750, ymn = -5350, ymx = 5850)

Arguments

dat

matrix of one of the allowed data types ("gfdl", "bootstrap", or "simple) (see details)

dat_type

string indicating the format of the data: either "gfdl", "bootstrap", or "simple" (see details)

level

concentration level of interest

my_land_mat

binary matrix specifying land locations

my_all_regions

SpatialPolygons object specifying region that will be considered

use_all

boolean, if true indicates to use the full area (overrides land_mat)

land_ind

boolean, if true indicates that the region of interest is the land

xmn

min x dimension (defaults to value for polar stereographic grid: -3850)

xmx

max x dimension (defaults to value for polar stereographic grid: 3750)

ymn

min y dimension (defaults to value for polar stereographic grid: -5350)

ymx

max y dimension (defaults to value for polar stereographic grix: 5850)

Value

region of interest as a SpatialPolygons object

Details

For datType = "simple" the values in the dat matrix are indicators of whether the grid box contains ice (1: ice-covered, 0: no ice, NA: land). If datType = "gfdl" or datType = "bootstrap", the values in the matrix correspond to the raw ice concentrations values observed or predicted (including indicators for missing data, land etc.). If datType = "gfdl", the predictions are formatted as in the CM2.5 Forecast-oriented Low-Ocean Resolution (FLOR) model produced by the National Oceanic and Atmospheric Administration<U+2019>s Geophysical Fluid Dynamics Laboratory converted to a Polar Stereographic grid (Vecchi et al. 2014; Msadek et al. 2014). If datType = "bootstrap" the array values are formatted the same as the ice concentration values obtained from the National Aeronautics and Space Administration (NASA) satellites Nimbus-7 SMMR and DMSP SSM/I-SSMIS and processed by the bootstrap algorithm.

References

Bootstrap sea ice concentration: Comiso, J., 2017: Bootstrap sea ice concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS. version 3. Boulder, Colorado USA: NASA National Snow and Ice Data Center Distributed Active Archive Center

CM2.5 Forecast-oriented Low-Ocean Resolution (FLOR) model:Vecchi, Gabriel A., et al. "On the seasonal forecasting of regional tropical cyclone activity." Journal of Climate 27.21 (2014): 7994-8016.

Msadek, R., et al. "Importance of initial conditions in seasonal predictions of Arctic sea ice extent." Geophysical Research Letters 41.14 (2014): 5208-5215.

Examples

# NOT RUN {
obs_example <-  get_region(dat = obsFeb2012, dat_type = "bootstrap", level = 15)
plot(land, col = 'grey', border = FALSE)
plot(obs_example, col = "lightblue", add = TRUE)
# }