snowdl

The goal of snowdl is to make it easy to download snow data (e.g., snow depth, snow density, snow-water equivalent) from various sources (see below).

Installation

Install the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("bsmity13/snowdl")

This package is not yet operational. Check back soon for progress!

Available data sources

Sorted alphabetically by dataset name

Dataset	Source	Link	Citation
Daymet v4	NASA	ORNL DAAC	Thornton et al. 2020
ERA5-Land Hourly	ECMWF	ERA5-Land	DOI: 10.24381/cds.e2161bac
SNODAS	NOAA	NSIDC	DOI: 10.7265/N5TB14TC

Important Notes

• Daymet is probably not a great source for SWE. Based on my reading, they treat it more like a nuisance parameter than a quanity of interest. See this link for their Snow Water Equivalent Clarification. Note, this clarification was made in reference to V3, but still applies based on newest literature for V4.

• Further, Daymet has (apparently) different units for SWE than other sources (but not really). Daymet uses kg/m^2, while other sources use m (depth if snow was melted). To convert, multiply by area of the pixel (kg/m^2 * m^2/1 = kg) to get mass of water, convert to cubic meters (1 kg = 1 L H2O = 0.001 m^3), and then get depth by dividing by area (m^3/1 * 1/m^2 = m). Perhaps more useful to have units in mm, so again multiply by 0.001 m = 1 mm.
  * Note Daymet comes with lcc projection and units = m. Resolution is 1000 x 1000, so area is 1e6 m^2.
  * Therefore, conversion becomes x * 1e6 * 0.001 * 0.001. All conversions cancel and resulting units are mm.
  * To be clear, kg/m^2 = mm in this case.

Package Status/To-dos

• Basic functionality
  • Download Daymet and process
  • Download ERA5 and process
  • Download SNODAS and process
• User-friendly wrappers
  • Iterate over dates
  • Complete entire workflow in tempdir()
• Other data sources?
• Vignettes
  • Overview/Quickstart using wrapper functions
  • In-depth using basic functionality