Author: Moritz Shore
Date: October, 2023
Introduction
The MET Nordic Reanalysis Dataset is a reanalysis product from the Meteorologisk institutt. You can read
more about the dataset here.
The MET Nordic rerun archive version 3 can be accessed using a dedicated
function in miljotools. Please inform yourself on the
limitations of reanalysis data before applying this dataset to your
needs.
Figure 1: The spatial domain of the reanalysis dataset.
Specs
1x1 km grid covering the Nordics (see Figure 1.)
Hourly resolution from 2012-09-01 to 2023-01-31
Following variables: temperature, precipitation, relative humidity, wind speed, wind direction, air pressure, cloud area fraction, short+longwave radiation (downwelling), land area fraction, and altitude
Input
To access the data for a specific region of the Nordics, you need to provide the following as input:
A path to a geo-referenced shapefile (single polygon) of the desired area
A directory where you would like to save the data (default: working directory)
A starting date and time
An ending date and time
Optionally, you can pass additional parameters to either buffer your shapefile, or to preview the data you are downloading.
download_folder <- get_metno_reanalysis3(
area = "C:/Users/morit/Documents/met_no/skuterud_wb.shp",
directory = "C:/Users/mosh/Documents/met_no",
fromdate = "2015-01-01 00:00:00",
todate = "2015-01-31 00:00:00",
area_buffer = 1500,
preview = T
)Output
Figure 2. Processing the shapefile and downloading relevant grid points.
As output you will receive a separate .csv file for each grid point. This .csv file contains the meteorological data as a timeseries, with a column for each variable. Additionally one metadata file is created listing the properties of each grid point (such as coordinates)
Note: Currently, this function must request the data from met.no server on an hour-basis. This means that for each year to download, 8760 requests must be made to the server. This is rather slow, and as such the download can take quite a few hours. We are working with met.no to improve this situation.
Conversion to Daily Data
If you would prefer to have your data in a daily format, you can use
the reanalysis3_daily() function. This function merely
requires the path of the download folder as created by
get_metno_reanalysis3(). You can pass a precision parameter
which determines to which decimal point the hourly data will be averaged
/ summed to.
daily_data_path <-
reanalysis3_daily(path = download_folder,
outpath = "C:/Users/mosh/Documents/met_no",
precision = 2)SWAT+ input generation from daily Reanalysis3 data
If you would like to generate SWAT+ meteo input from the daily data
as downloaded get_metno_reanalysis3() and converted from
reanalysis3_daily(), you can use the
reanalysis3_swatinput() function. This function, depending
on the parameters given to it, will generate your station files and
weather generator. It also can update your SWAT+ input files to match
the new weather stations, or update your .sqlite database.
To do this, the function heavily utilizes SWATprepR which
needs to be installed before use. This can be done here.
reanalysis3_swatinput(path = daily_data_path,
swat_setup = "C:/path/to/swat/txtinout")Reanalysis to SWAT+ input pipeline
The aforementioned three function can be linked together with the
swat_weather_input_chain(). It simply runs the three
functions in parallel, allowing you to generate and apply weather data
to your SWAT+ project with one line of code.
swat_weather_input_chain(
area = "C:/Users/mosh/Documents/skuterud_wb.shp",
swat_setup = "C:/path/to/swat/txtinout",
directory = "path/to/working/directory",
from = "2013-01-01 00:00:00",
to = "2022-12-31 00:00:00"
)