Add NSIDC sea ice concentration data (#53)

input_data/NSIDC_Sea_Ice/meta.yaml

+repo_name: NSIDC_Sea_Ice
+
+people: Willi Rath (<wrath@geomar.de>)
+
+http_path_remote: https://git.geomar.de/data/NSIDC_Sea_Ice
+
+git_path_remote: git@git.geomar.de:data/NSIDC_Sea_Ice
+
+repo_description: |
+     NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration,
+     Version 3
+
+     <http://nsidc.org/data/G02202/versions/3>
+
+prefixes: data doc
+
+data:
+
+    - url: "ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G02202_V3/"
+      cut_dirs: 4
+      prefix: data
+      accept_files: "*.*"
+      method: !!python/name:data_repo_renderer.WgetRecursive
+
+doc:
+
+    - url: "http://nsidc.org/sites/nsidc.org/files/technical-references/SeaIce_CDR_CATBD_final_Rev-5.pdf"
+      file_name: SeaIce_CDR_CATBD_final_Rev-5.pdf
+      prefix: doc
+      method: !!python/name:data_repo_renderer.CurlSingleFile
+
+    - url: "https://www.earth-syst-sci-data.net/5/311/2013/essd-5-311-2013.pdf"
+      file_name: essd-5-311-2013.pdf
+      prefix: doc
+      method: !!python/name:data_repo_renderer.CurlSingleFile
+
+    - url: "http://nsidc.org/data/G02202/versions/3/print/"
+      file_name: nsidc.org_data_G02202_versions_3_print.html
+      prefix: doc
+      method: !!python/name:data_repo_renderer.CurlSingleFile
+
+post_processing:
+
+    - util/convert_to_netCDF4_classic.sh

input_data/NSIDC_Sea_Ice/util/convert_to_netCDF4_classic.sh

+#!/bin/bash
+
+# define and export convert function
+function convert_to_nc4c {
+    file_name=$1
+    echo "converting ${file_name}"
+    nccopy -7 -d 1 -s -c "time/1,ygrid/100,xgrid/100" \
+        ${file_name} ${file_name}_tmp_nc4
+    mv ${file_name}_tmp_nc4 ${file_name}
+}
+export -f convert_to_nc4c
+
+# bunzip and convert using 4 threads
+find data/ -type f -iname \*.nc -print0 | \
+    xargs -0 -n1 -P4 -I {} bash -c "convert_to_nc4c {}"