3.1. Meteorological Data: Download data (ERA5)

Note

(February/2020) This plugin replaces the WATCH download plugin. To make use of this plugin you need to make additional configurations outside QGIS/UMEP (see below).

Note

ERA5 data is adjusted to UTC = 0. This has implications for other tools in UMEP (see respective tool documentation).

Contributors：

Name

Institution

Ting Sun

Reading

Fredrik Lindberg

Gothenburg
Introduction：
Basic meteorological variables are required for most applications in the UMEP processor. If observed data are not available for a particular location, hourly data can be retrieved from the global the Coopernicus programme and thier Climate Data Store. This plugin allows climate reanalysis data to be extracted for a specific location and period of interest (1979-2020), and transformed into formatted forcing files suitable for models within UMEP.

Variables available	Comments
Wind speed [m s^-1]	10 m instantaneous
Air temperature [K]	2 m instantaneous
Specific humidity [kg kg^-1]	2 m instantaneous
Pressure [Pa]	Instantaneous surface pressure
Incoming shortwave radiation [W m^-2]	Average over previous 1 hour
Incoming longwave radiation [W m^-2]	Average over previous 1 hour
Rainfall rate [kg m^-2 s^-1]	Average over previous 1 hour

Configuring your computer to enable download：
- You might need to install/update the SuPy library. Follow the instruction at link (pip install supy –upgrade).
  
  If your computer is not configured for downloading data from the Climate Data Store, follow the instructions here. You only need to consider the section Install the CDS API key.
Obtaining ERA5 data via UMEP：

Fig. 3.1 ERA5 data downloader (UMEP for Processing): control panel
Running the tool：
The downloader is separated into two sections:
Download climate data: Retrieves ERA5 data for all variables for the location and period of interest.

Latitude and longitude: WGS84 co-ordinates of the study location. Data is extracted from the ERA5 grid cell that contains these co-ordinates.

Start time and End Time: The time range of data to be downloaded
Considerations：
- Spatial resolution: The ERA5 data are provided for half-degree grid boxes. In regions with substantial heterogeneity within these grid boxes data at the grid-box scale may be not be representative of your study site (e.g. mountainous regions, urban areas).
- Downloading long time series: The cdsapi can sometime be very busy and slow. The we recommend you to use www.shinyweatherdata.com where the same data can be downloaded at much faster speed.

Name	Institution
Ting Sun	Reading
Fredrik Lindberg	Gothenburg