The collection of scripts download Historical ERA5 data, ECMWF 10-day forecasts to create a continuous dataset for 2 years into the past

Background and Requirements

• Data sources:

1. ERA5 historical data - https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=overview https://confluence.ecmwf.int/pages/viewpage.action?pageId=228867588
2. ECMWF 10-day forecasts - https://www.ecmwf.int/en/forecasts/datasets/set-i

• The era5 data is accessed via the Copernicus Data Server (CDS) using a python script, please follow the instructions here to setup access

• The forecast data is accessed via the ECMWF API, please follow the instructions here to create an account and get access to the ECMWF API. Also check how to setup the ECMWF API key under your home directory.

• The scripts are run on the Pearcey HPC

• To run, use the command sbatch --array=0-5 era5_download.sh

Climate Variables

1. 2m temperature - daily_maximum
2. 2m temperature - daily_minimum
3. Precipitation - daily_total
4. Daily potential evaporation
5. Soil temperature: 0 --7cm - daily_minimum
6. Soil temperature: 0--7cm - daily_maximum

Steps

The output continuous dataset will combine the historical and forecast data in the following way

1. Download ERA5 dataset dating back 2 years

• ERA5 historical reanalysis data: 2 years in the past to 3 month before current month
• Summary of era5 data downloaded from era5_download.sh and era5_download.py

Variable	dimensions	Name of variable: Long name	Raw data unit	Unit to be converted to
tasmax	time=xx lat=1801 lon=3601	Tas (time,lat,lon)	K	C = -273.15
tasmin	time=xx lat=1801 lon=3601	Tas (time,lat,lon)	K	C = -273.15
Mean_precip	time=xx lat=1801 lon=3601	Tprate (time,lat,lon) Total precipitation rate	m s-1	mm d-1 = (1000)x(606024)
Mean_pev	time=xx lat=1801 lon=3601	pev (time,lat,lon) thickness of the liquid water equivalent potential evaporation amount	m	mm = 1000
soil_tmax	time=xx lat=1801 lon=3601	stl1 (time,lat,lon) top soil layer temperature	K	C = -273.15
soil_tmin	time=xx lat=1801 lon=3601	stl1 (time,lat,lon) top soil layer temperature	K	C = -273.15

2. Download the ECMWF 10-day forecasts dating back 3 months and 10 days into the future

• ECMWF 10-day forecasts: 3 months in the past until most recent predictions (pseudo-observations)
• ECMWF 10-day forecasts: 10-days into the future
• Data are available at 6-hour intervals
• Add up 4 x 6-hour data for each day, converting 10-day forecast into daily summaries

3. Continuously update the datasets updating can happen once per week. In conclusion, each week, we should provide 2 yrs + 10 day forecast into the future