MEaSURes 25KM snow cover data downloadSean SultaireNovember 5, 2015Data category: Climate data Data Description: MEaSUReS 25km resolution snow cover data can be obtained daily for the entire northern hemisphere between 1999 and 2012. It contains 4 different model derived snow cover variables, one of which is used here. Data use policy: at Data link Use with R: The snow cover data is available on a NASA FTP server. The following script recursively downloads NETCDF files from the NASA ftp server (1 for each day) with package RCurl. It then processes the nc files using the packages ncdf and ncdf4 into a usable raster stack (raster package).
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Spatial Data: Climate Data from PRISM Climate GroupData Category: Climate Data Data Description: PRISM Climate Group provides climate observations that has been gathered to show short and long term patterns. Most of the time this data is free except when data sets become large/complex. This data goes back to 1895 and up to present day. This data cover the contiguous United States. Data Link: http://www.prism.oregonstate.edu/ Data Use Policy: http://http://www.prism.oregonstate.edu/documents/PRISM_terms_of_use.pdf Use with R: For PRISM Climate Data, you need to manually download the file to you computer. You can do this by going to the PRISM website and downloading whatever data you want. http://www.prism.oregonstate.edu/normals/ Packages to Load:
Here I am doing the mean Minimum Temperature over the last 30 years. After you download the file, you will need to unzip the folder. Set up your working directory to where you unzipped your files.
Your next step is to create the raster.
Now you can plot your raster.
Spatial Data: Land Cover Type from MRLC NLCDData Category: Land Cover Type Data Description: The National Land Cover Database (NLCD) is a compilation of land cover data collected and maintained by the Multi-Resolution Land Characteristics (MRLC). Data Link: http://www.mrlc.gov/index.php Data Use Policy: http://www.usgs.gov/laws/policies_notices.html Use With R: When using NLCD data with R, the information can be downloaded from the MRLC website (link above). Note that this data set can be memory intensive for an average computer. Due to the size of the data file (i.e., the entire U.S.A.) it may take a considerable amount of time to retrieve and plot. Once rasterized, it is possible to decrease the resolution of the data (depending on your scale of interest) to reduce the size of the file, as demonstrated in the following example, before plotting the data. Decreasing the resolution may not be desirable in many situations so keep in mind the scale and region size of interest. Useful packages for working with this data in R include “raster” in order to rasterize the data. In this example, I have downloaded the entire continental U.S. and presented it at a resolution of 100 m. Install and load relevant packages
Download data
Unzip data
Rasterize the data (package “raster”)
Change the resolution of the data to decrease file size using aggregate()
Plot the NLCD data
Further: The information provided here http://neondataskills.org/R/Raster-Data-In-R/ may be useful in producing a map with more distinct color, as shown below: |
Spatial Ecology @ MSUClick on "Category" below to search for R code compiled by the Zarnetske Spatial & Community Ecology Lab and students in MSU's Spatial Ecology graduate course (FOR870/FW870) Category
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