zonalDaymet provides tools to establish a relationship between
Daymet daily climate records and user-provided
spatial polygons within the R environment. The package gives the user
flexibility to index, concatenate, and average climate records in specified
locations.
Daily surface weather and climatalogical summaries are provided in
netCDF format. Each netCDF mosaic file contains the record for a single variable
over 1 year (1980 - present) across a 1 km2 resolution grid over
North America. Each point location in the grid, specified by latitude/longitude
coordinates, has a climatological time series associated with it for the
specified variable in the file. For example, the prcp_1980.nc4 mosaic file
contains the daily gridded precipitation record across North America for 1980. In
the case of a leap year, the December 31st record is omitted.
The package provides tools to accomplish the following:
- Download netCDF climate mosaics from the Daymet THREDDS Server
- Iterate through netCDF files combining time series records and variables into tables
- Spatially average climate records within user-specified spatial polygons
- Divide spatial objects into manageable pieces within the R environment to avoid memory issues during spatial averaging
- Return subsets from the climate mosaics given latitude/longitude coordinate bounds
Functionality is provided to return spatial averages as either a dataframe in the current R environment or write directly to a SQLite database. If a polygon is too small to warrant a spatial average of points, the nearest point is assigned to the polygon. A function is also provided to simplify record selection from the database.
The [Sample-Workflow Vignette](https://github.com/Conte-Ecology/zonalDaymet/blob/master/vignettes/Sample Workflow.md) provides a walk-through of the package functions and how they can be used together to process the Daymet netCDF mosaic files into a more useful format in R.
Currently, the package is only available through GitHub. It can be installed using the devtools package by executing the following commands in the R workspace:
library(devtools)
install_github("Conte-Ecology/zonalDaymet")
library(zonalDaymet)
Kyle O'Neil
koneil@usgs.gov