All ER5 data comes from the montly, single-levels set:

    ERA5 monthly averaged data on single levels from 1979 to present
    DOI: 10.24381/cds.f17050d7

A preliminary version of the 1950 to 1978 data is also available:

    https://cds.climate.copernicus-climate.eu/cdsapp#!/dataset/reanalysis-era5-single-levels-preliminary-back-extension?tab=overview

Here is the list of variables we use to get atmospheric fluxes in kg s**-1:

Mean total precipitation rate	kg m**-2 s**-1

	This parameter is the rate of precipitation at the Earth's surface. 
	It is the sum of the rates due to large-scale precipitation and 
	convective precipitation. Large-scale precipitation is generated by 
	the cloud scheme in the ECMWF Integrated Forecasting System (IFS). 
	The cloud scheme represents the formation and dissipation of clouds 
	and large-scale precipitation due to changes in atmospheric 
	quantities (such as pressure, temperature and moisture) predicted 
	directly at spatial scales of the grid box or larger. Convective 
	precipitation is generated by the convection scheme in the IFS, 
	which represents convection at spatial scales smaller than the grid 
	box. In the IFS, precipitation is comprised of rain and snow. This 
	parameter is a mean over a particular time period (the processing 
	period) which depends on the data extracted. For the monthly 
	averaged reanalysis and the monthly averaged ensemble members, the 
	processing period is the complete, whole month. For the monthly 
	averaged reanalysis by hour of day, the processing period is 1 hour 
	for every day of the month and for the monthly averaged ensemble 
	members by hour of day, the processing period is 3 hours for every 
	day of the month. It is the rate the precipitation would have if it 
	were spread evenly over the grid box. 1 kg of water spread over 1 
	square metre of surface is 1 mm deep (neglecting the effects of 
	temperature on the density of water), therefore the units are 
	equivalent to mm (of liquid water) per second. Care should be taken 
	when comparing model parameters with observations, because 
	observations are often local to a particular point in space and 
	time, rather than representing averages over a model grid box.

Mean evaporation rate	kg m**-2 s**-1

	This parameter is the amount of water that has evaporated from the 
	Earth's surface, including a simplified representation of 
	transpiration (from vegetation), into vapour in the air above. This 
	parameter is a mean over a particular time period (the processing 
	period) which depends on the data extracted. For the monthly 
	averaged reanalysis and the monthly averaged ensemble members, the 
	processing period is the complete, whole month. For the monthly 
	averaged reanalysis by hour of day, the processing period is 1 hour 
	for every day of the month and for the monthly averaged ensemble 
	members by hour of day, the processing period is 3 hours for every 
	day of the month. The ECMWF Integrated Forecasting System (IFS) 
	convention is that downward fluxes are positive. Therefore, 
	negative values indicate evaporation and positive values indicate 
	condensation.

Vertical integral of eastward water vapour flux	kg m**-1 s**-1

	This parameter is the horizontal rate of flow of water vapour, in 
	the eastward direction, per metre across the flow, for a column of 
	air extending from the surface of the Earth to the top of the 
	atmosphere. Positive values indicate a flux from west to east.

Vertical integral of northward water vapour flux	kg m**-1 s**-1

	This parameter is the horizontal rate of flow of water vapour, in 
	the northward direction, per metre across the flow, for a column of 
	air extending from the surface of the Earth to the top of the 
	atmosphere. Positive values indicate a flux from south to north.

Vertical integral of eastward cloud liquid water flux	kg m**-1 s**-1

	This parameter is the horizontal rate of flow of cloud liquid 
	water, in the eastward direction, per metre across the flow, for a 
	column of air extending from the surface of the Earth to the top of 
	the atmosphere. Positive values indicate a flux from west to east.

Vertical integral of northward cloud liquid water flux	kg m**-1 s**-1

	This parameter is the horizontal rate of flow of cloud liquid 
	water, in the northward direction, per metre across the flow, for a 
	column of air extending from the surface of the Earth to the top of 
	the atmosphere. Positive values indicate a flux from south to 
	north.

Vertical integral of eastward cloud frozen water flux	kg m**-1 s**-1

	This parameter is the horizontal rate of flow of cloud frozen 
	water, in the eastward direction, per metre across the flow, for a 
	column of air extending from the surface of the Earth to the top of 
	the atmosphere. Positive values indicate a flux from west to east. 
	Note that "cloud frozen water" is the same as "cloud ice water".

Vertical integral of northward cloud frozen water flux	kg m**-1 s**-1

	This parameter is the horizontal rate of flow of cloud frozen 
	water, in the northward direction, per metre across the flow, for a 
	column of air extending from the surface of the Earth to the top of 
	the atmosphere. Positive values indicate a flux from south to 
	north. Note that "cloud frozen water" is the same as "cloud ice 
	water".



We also calculate basin averages for the following variables:

Leaf area index, high vegetation	m**2 m**-2

	This parameter is the surface area of one side of all the leaves 
	found over an area of land for vegetation classified as "high". 
	This parameter has a value of 0 over bare ground or where there 
	are no leaves. It can be calculated daily from satellite data. It 
	is important for forecasting, for example, how much rainwater will 
	be intercepted by the vegetative canopy, rather than falling to 
	the ground. This is one of the parameters in the model that 
	describes land surface vegetation. "High vegetation" consists of 
	evergreen trees, deciduous trees, mixed forest/woodland, and 
	interrupted forest.

Leaf area index, low vegetation	m**2 m**-2

	This parameter is the surface area of one side of all the leaves 
	found over an area of land for vegetation classified as "low". 
	This parameter has a value of 0 over bare ground or where there 
	are no leaves. It can be calculated daily from satellite data. It 
	is important for forecasting, for example, how much rainwater will 
	be intercepted by the vegetative canopy, rather than falling to 
	the ground. This is one of the parameters in the model that 
	describes land surface vegetation. "Low vegetation" consists of 
	crops and mixed farming, irrigated crops, short grass, tall grass, 
	tundra, semidesert, bogs and marshes, evergreen shrubs, deciduous 
	shrubs, and water and land mixtures.

2m dewpoint temperature	K

	This parameter is the temperature to which the air, at 2 metres 
	above the surface of the Earth, would have to be cooled for 
	saturation to occur. It is a measure of the humidity of the air. 
	Combined with temperature and pressure, it can be used to calculate 
	the relative humidity. 2m dew point temperature is calculated by 
	interpolating between the lowest model level and the Earth's 
	surface, taking account of the atmospheric conditions. This 
	parameter has units of kelvin (K). Temperature measured in kelvin 
	can be converted to degrees Celsius (°C) by subtracting 273.15.

2m temperature	K

	This parameter is the temperature of air at 2m above the surface of 
	land, sea or inland waters. 2m temperature is calculated by 
	interpolating between the lowest model level and the Earth's 
	surface, taking account of the atmospheric conditions. This 
	parameter has units of kelvin (K). Temperature measured in kelvin 
	can be converted to degrees Celsius (°C) by subtracting 273.15.



Here are the column descriptions for the *_output.csv files

date        Date [YYYY-MM-DD]
water_vap   Water vapor [kg/s]
water_liq   Cloud liquid water [kg/s]
water_ice   Cloud fozen water [kg/s]
prec        Precipitation [kg/s]
evap        Evaporation [kg/s]
temp_2m     Temperature at 2 meter [K]
dew_2m      Dewpoint temperature at 2 meter [K]
lai_lv      Leaf Area Index, low vegetation [m**2/m**2]
lai_hv      Leaf Area Index, high vegetation [m**2/m**2]
discharge   Mean monthly discharge (from GRDB) [m**3/s]
