metnodi

The goal of metnodi is to provide an interface to the met Nordic data (metnodi stands for met Nordic data interface). For a detailed description of this data and links to the original source please see the met Nordic github page. Currently, the package merely simplifies the download of targeted weather data from thredds.met.no, and saves this data in convenient netcdf format. It supports downloading for target locations (finding the nearest neighbor gridcells of the MET Nordic data), or a rectangular area (in lon/lat). Moreover, downloads are pooled in time into either daily-, monthly-, yearly- or a single file, depending on the size of the downloaded area. This format is more convenient to work with than the original format, which is a single netcdf per hour. The package also has functions for plotting and loading the downloaded data.

Installation

You can install the development version of metnodi from GitHub with:

# install.packages("devtools")
devtools::install_github("NorskRegnesentral/metnodi")

Example

This is a basic example which shows you how to download data:

library(metnodi)

### downloading past analysis for a rectangular area ###

# area around Oslo
lon_min = 8
lon_max = 12
lat_min = 58
lat_max = 62

time_start = "2024-01-01"
time_end = "2024-01-03"

# download all available weather variables in this area and store it in a temporary file:

download_metno_analysis_rect(file_out = 'oslo_weather_202401.nc', 
                             out_dir = tempdir(),
                             bbox = c(lon_min,lat_min,lon_max,lat_max),
                             time_start = time_start,
                             time_end = time_end)

### downloading data for specific locations ###

# Here, we only download precipitation. Use weather_variables() to see the names of all available weather variables 

# some locations in the area around Oslo:
coords = data.table(lon = runif(50,min = lon_min, max = lon_max),
                    lat = runif(50,min = lat_min, max = lat_max))

download_metno_analysis_nn(file_out = 'random_locs_weather_202401.nc', 
                           out_dir = tempdir(),
                           coords = coords,
                           time_start = time_start,
                           time_end = time_end,
                           vars = 'precipitation_amount')


### download latest forecasts ###

download_metno_fc_rect(file_out = 'oslo_precip_fc.nc', 
                       out_dir = tempdir(),
                       bbox = c(lon_min,lat_min,lon_max,lat_max),
                       time_start = 'all',
                       initialization_time = 'latest')


download_metno_fc_nn(file_out = 'random_locs_precip_fc.nc', 
                     out_dir = tempdir(),
                     coords = coords,
                     time_start = 'all',
                     initialization_time = 'latest')


### plotting ###

# here we plot the first time-slice of precipitation downloaded above:

st = read_stars_metno(paste0(tempdir(),'/oslo_weather_202401.nc'),var = 'precipitation_amount')
pp = gmaps_plot(st) + ggplot2::scale_fill_gradient(name = 'mm',low = 'white',high = 'blue')
plot(pp)