How to Open and Work with NetCDF Data in R
Presented by the ORNL DAAC https://daac.ornl.gov
March 26, 2018
Keywords: R, netCDF
UPDATE: The repo was updated on 2021-12-03 and again on 2024-01-02. The recent update includes a revision of the tutorial to replace deprecated packages (e.g., rgdal and raster).
1. Overview
In this tutorial we will open some geospatial data that is stored in a netCDF file. Then we will select the variable and time range of interest and export the data as a GeoTIFF file so that we can continue the analysis in R or other geospatial software.
2. Dataset
Long-Term Arctic Growing Season NDVI Trends from GIMMS 3g, 1982-2012
The dataset used in this tutorial provides normalized difference vegetation index (NDVI) data for the Arctic growing season derived primarily with data from Advanced Very High Resolution Radiometer (AVHRR) sensors on board several NOAA satellites over the years 1982 through 2012. The NDVI data, which show vegetation activity, were averaged annually for the arctic growing season (June, July, and August) in each year. The data are circumpolar in coverage at 8-kilometer resolution and limited to greater than 20 degrees North.
Guay, K.C., P.S.A. Beck, and S.J. Goetz. 2015. Long-Term Arctic Growing Season NDVI Trends from GIMMS 3g, 1982-2012. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1275
Specifically, we will use the file “gimms3g_ndvi_1982-2012.nc4”. With a single click, download the data here https://daac.ornl.gov/daacdata/global_vegetation/GIMMS3g_NDVI_Trends/data/gimms3g_ndvi_1982-2012.nc4 before beginning the tutorial.
3. Prerequisites
Participants should have a basic understanding of R.
3.1 R
- Download R
- Download RStudio Recommended
- Review R Manuals Recommended