Get_Arctic_Sea_Ice: Download Arctic Sea Ice Concentrations from NSIDC

In chihlinwei/OceanData: Tools to download and extract oceanographic data from various sources

Download Arctic Sea Ice Concentrations from NSIDC

Description

Download National Snow and Ice Data Center (NSIDC) Arctic Sea Ice Concentrations binary flat file and then convert to a raster object

Usage

Get_Arctic_Sea_Ice(url, x = NULL, outdir = NULL, plot = FALSE)

Arguments

url	A character string naming the URL of a binary file to be downloaded
x	Raster* object defining the spatial extent, resolution and projection of sea ice data to be retrived. If not provide, returning full data set.
outdir	output directory to write raster file
plot	Logical, whether or not to plot the output raster

Details

This function dowloads the northern hemisphere NSIDC Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data (http://nsidc.org/data/nsidc-0051.html). Function was Modified from codes written by Tony Fischbach at Walrus Research Program, Alaska Science Center, USGS. Metadata information for the northern hemisphere sea ice data is available at https://support.nsidc.org/entries/21680984-How-do-I-import-the-0051-sea-ice-concentration-data-into-ArcGIS-

Value

a raster object

Author(s)

Chih-Lin Wei <[e-mail]>

Examples

# Raster template of Canadian Arctic
data(tmp)

# Download January 1998 data as an example
url <- "ftp://sidads.colorado.edu/pub/DATASETS/nsidc0051_gsfc_nasateam_seaice/final-gsfc/north/monthly/nt_199801_f13_v01_n.bin"
Get_Arctic_Sea_Ice(url=url, x=tmp, plot=TRUE)

# Use foreach loop to download sea ice data for all months from 1998 to 2012
library(RCurl) 
library(foreach)
library(doSNOW)

url<-c("ftp://sidads.colorado.edu/pub/DATASETS/nsidc0051_gsfc_nasateam_seaice/final-gsfc/north/monthly/")
filenames = getURL(url, ftp.use.epsv = FALSE, ftplistonly = TRUE, crlf = TRUE) 
filenames = paste(url, strsplit(filenames, "\r*\n")[[1]], sep = "")

# Create a folder to save raster files
folder <- "../Arctic_ocean_data/Sea_Ice_Nimbus-7_SMMR_DMSP_SSMI_SSMIS/" 
dir.create(folder)

cl<-makeCluster(4) # change 4 to your number of CPU cores
registerDoSNOW(cl) # register the SNOW parallel backend with the foreach package
foreach(i = filenames[232:423], .packages="OceanData") %dopar% Get_Arctic_Sea_Ice(i, tmp, folder)
stopCluster(cl) # stop a SNOW cluster

chihlinwei/OceanData documentation built on Jan. 17, 2025, 4:24 a.m.