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The production of the CERRA system data is delayed by 2-3 months with respect to real time. For instance, the release of data for January 2023 can be expected in April 2023. The delay is directly dependent on the availability of some reprocessed dataset datasets (e.g. GNSS-RO).

• Can we use reanalysis data for local applications?

Note: at the time when the dataset was released, a contract for the near-real time update of CERRA dataset had not been concluded, and therefore the production was suspended; it will be resumed once the contract is signed. One should be aware that it takes several months to produce data that will bridge the gap between June 2021 (last available month) and the near-real time, and that only after filling the gap, the dataset will be updated with a delay of 2-3 months behind the real time. For instance, the release of data for January 2023 can be expected in April 2023.

• Can we use reanalysis data for local applications?

Reanalysis data are gridded products. The values represent a certain spatial scale which may be hard to compare to a point value that may be obtained from a station. The horizontal grid resolution of the reanalysis is 5.Reanalysis data are gridded products. The values represent a certain spatial scale which may be hard to compare to a point value that may be obtained from a station. The horizontal grid resolution of the reanalysis is 5.5 km and hence a grid box has an area of 30.25km². Given values are usually a mean for the entire grid area whereas station data represent only a single point. Hence, the spatial scales of the data are not the same.

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The used grids are in the Lambert Conformal Conic projection with parameters according to section 5.1.6 for CERRA. There are no defined EPSG codes for these specific projections, but there is a general definition of Lambert Conformal Conic with 2 standard parallels in EPSG:9802.
The coordinate systems are often problematic when handling model output, but a great improvement is that nowadays many available programs are able to handle GRIB files and especially the projection information that is embedded in GRIB files. For example, later versions of many GIS tools (e.g QGIS, ArcGIS) can open and georeference the grib files out of the box. Just drag and drop a grib GRIB file into the GIS tool and it should open up, see Fig. 9. This can be a good starting point for getting to know the grid and handle the projection.

Figure 9: A CERRA-Land grib GRIB file opened in QGIS. To the left in the Lambert Conformal Conic projection, to the right transformed to WGS 84.

Detailed data description and availability

CERRA

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Parameters on single level

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10m wind speed

The 210-metre (2m) relative humidity (parameter name: surface air relative humidity) is the modelled humidity 10m) wind speed is the wind speed valid for the grid area (approximately 5.5km*5.5km = 30.25km²) determined for a height of 2m 10m above the surface. The parameter is given in %, and is the relation between actual humidity and saturation humidity. Values are in the interval [0,100]. 0% means that the air is totally dry whereas 100% indicates that the air is saturated with water vapour. The saturation is defined with respect to saturation of the mixed phase, i.e. with respect to saturation over ice below -23°C and with respect to saturation over water above 0°C. In the regime in between a quadratic interpolation is applied. Surface air relative humidity is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time m/s. It is computed from both the zonal (u) and the meridional (v) wind components by wind speed=u²+v². The 10m wind speed is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Total column integrated water vapour

10m wind gust since previous post-processing 

The 10-metre (10m) wind gust is a diagnostic variable. The parametrization is based on wind speed and turbulence. A 3s wind gust is computed every time step and the maximum is kept since the last post-processing at the grid area. It is determined for a height of 10m above the surfaceThe total column integrated water vapour is the vertically integrated water vapour (precipitable water content) valid for the grid area. It is vertically integrated from the surface to the top of the atmosphere. The parameter is given in kgm/m². Total column water vapour is s. The 10m wind gust is only available for the analysis and the forecast time steps. The value is the maximum since the previous post-processing. For instance, for the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Total precipitation

Total precipitation is the amount of precipitation falling onto the ground/water surface. It includes a few types of precipitation forms such as convective precipitation, large scale precipitation, liquid and solid precipitation. The amount is valid for the grid area and has the unit kg/m². The total precipitation is available only for the forecast time steps. It is an accumulated parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated precipitation over 24 hours. The total amount of rain might be computed by subtracting the snowfall water equivalent from the total precipitation.

10m wind speed

first saved time step at forecast 1h it is the maximum wind speed, which occurred within the first hour of the forecast. For the second saved time step at forecast 2h, it is the maximum wind speed which happened in the second forecast hour, hence between fc1 and fc2. For longer forecasts, the output frequency is reduced. Hence, the maximum over a longer time period is saved. For instance, for the 15h forecast the maximum wind speed is identified within the period 12h – 15h since the last post-processing happened at 12h (12 hours after the onset of the forecast).

10m wind direction

The 10-metre wind direction is the wind direction The 10-metre (10m) wind speed is the wind speed valid for the grid area determined for a height of 10m above the surface. The parameter is given in m/s. It is computed from both the zonal (u) and the meridional (v) wind components by wind speed=u²+v². The 10-m wind speed degrees ranging from 0-360. Here, 0° means a northerly wind and 90° indicates an easterly wind. The 10m wind direction is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

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2m relative humidity

The 102-metre wind direction (2m) relative humidity is the wind direction modelled air humidity valid for the grid area determined for a height of 10m above the surface. (approximately 5.5km*5.5km = 30.25km²) determined for a height of 2m above the surface.  It expresses the relation between actual humidity and saturation humidity. The parameter is given in degrees ranging from 0-360. Here, 0° means a northerly wind and 90° indicates an easterly wind. The 10-m wind direction is available for the analysis and the forecast time steps. For the forecast, in %. Values are in the interval [0,100]. 0% means that the air is totally dry whereas 100% indicates that the air is saturated with water vapour. The saturation is defined with respect to saturation of the mixed phase, i.e. with respect to saturation over ice below -23°C and with respect to saturation over water above 0°C. In the regime in between a quadratic interpolation is applied. 2m relative humidity is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

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2m temperature

The 10-metre (10m) wind gust speed is a diagnostic variable. The parametrization is based on wind speed and turbulence. A 3s gust is computed every time step and the maximum is kept since the last post-processing at the grid area. It is 2-metre temperature with the parameter name surface air temperature is the model temperature valid for the grid area determined for a height of 10m 2m above the surface. The parameter is given in m/s. The 10-m wind gust speed is only Surface air temperature is available for the analysis and the forecast time steps. The For the forecast, the value is the maximum since the previous post-processing. For instance, for the first saved time step at forecast 1h it is the maximum wind speed, which occurred within the first hour of the forecast. For the second saved time step at forecast 2h, it is the maximum wind speed which happened in the second forecast hour, hence between fc1 and fc2. For longer forecasts, the output frequency is reduced. Hence, the maximum over a longer time period is saved. For instance, for the 15h forecast the maximum wind speed is identified within the period 12h – 15h since the last post-processing happened at 12h (12 hours after the onset of the forecast).

Surface air maximum temperature

The surface air maximum temperature is the maximum temperature since the last post-processing at the grid area. It is determined for a height of 2m above the surface. The parameter is given in Kelvin [K]. Surface air maximum temperature is only available for the forecast time steps. The value is the maximum since the previous post-processing. For instance, for the first saved time step at forecast 1h it is the maximum surface air temperature, which occurred within the first hour of the forecast. For the second saved time step at forecast 2h, it is the maximum surface air temperature which happened in the second forecast hour, hence between fc1 and fc2. For longer forecasts, the output frequency is reduced. Hence, the maximum over a longer time period is saved. For instance, for the 15h forecast the maximum surface air temperature is identified within the period 12h – 15h since the last post-processing happened at 12h (12 hours after the onset of the forecast).

Surface air minimum temperature

The surface air minimum temperature is the minimum temperature since the last post-processing at the grid area. It is determined for a height of 2m above the surface. The parameter is given in Kelvin [K]. Surface air minimum temperature is only available for the forecast time steps. The value is the minimum since the previous post-processing. For instance, for the first saved time step at forecast 1h it is the minimum surface air temperature, which occurred within the first hour of the forecast. For the second saved time step at forecast 2h, it is the minimum surface air temperature which happened in the second forecast hour, hence between fc1 and fc2. For longer forecasts, the output frequency is reduced. Hence, the minimum over a longer time period is saved. For instance, for the 15h forecast the minimum surface air temperature is identified within the period 12h – 15h since the last post-processing happened at 12-h (12 hours after the onset of the forecast).

2m temperature

The 2-metre temperature with the parameter name surface air temperature is the model temperature valid for the grid area determined for a height of 2-m above the surface. The parameter is given in Kelvin [K]. Surface air temperature is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. 

Skin temperature

The skin temperature is the model temperature valid for the grid area determined for the boundary surface to the atmosphere, both ground and water surfaces. The parameter is given in Kelvin [K]. Skin temperature is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. 

Albedo

The albedo is the amount of radiation which is reflected for the given grid area. It is determined for the surface to the atmosphere, both for ground and water surfaces. The parameter is given in %. Small values mean that large amounts of the radiation are absorbed whereas large values mean that more radiation is reflected. Albedo is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Evaporation

Evaporation is the amount of moisture flux from the surface (ground and water) into the atmosphere. It is given as a mean for the grid area. The mean is a weighted average over all tile types present in the grid point. The parameter is given in kg/m². By model convention downward fluxes are positive. Hence, evaporation is represented by negative values and positive values represent condensation. Evaporation is only available for forecast time steps. It is an accumulated parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated evaporation over 24 hours.

Time-integrated surface latent heat flux

The surface latent heat flux is the exchange of latent heat (due to phase transitions: evaporation, condensation) with the surface (ground and water) through turbulent diffusion. It is the mean for the grid area. The parameter is given in J/m². By model convention downward fluxes are positive. Surface latent heat flux is only available for forecast time steps up to forecast hour six. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated heat flux over 24 hours.

Time-integrated surface sensible heat flux

The surface sensible heat flux is the exchange of heat (no phase transition) with the surface (ground and water) through turbulent diffusion. It is given as a mean for the grid area. The parameter is given in J/m². By model convention downward fluxes are positive. Surface sensible heat flux is only available for forecast time steps up to forecast hour six. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated heat flux over 24 hours.

Time-integrated surface direct solar radiation

instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The parameter is given in Kelvin [K].

Albedo

The albedo is the amount of radiation which is reflected for the given grid area. It is determined for the surface to the atmosphere, both for ground and water surfaces. The parameter is given in %. Small values mean that large amounts of the radiation are absorbed whereas large values mean that more radiation is reflected. Albedo is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Evaporation

Evaporation is the amount of moisture flux from the surface (ground and water) into the atmosphere. It is given as a mean for the grid area. The mean is a weighted average over all tile types present in the grid point. By model convention downward fluxes are positive. Hence, evaporation is represented by negative values and positive values represent condensation. Evaporation is only available for forecast time steps. It is an accumulated parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated evaporation over 24 hours. The parameter is given in kg/m².

Total column integrated water vapour

The total column integrated water vapour is the vertically integrated water vapour (precipitable water content) valid for the grid area. It is vertically integrated from the surface to the top of the atmosphere. Total column water vapour is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The parameter is given in kg/m².

Total precipitation

Total precipitation is the amount of precipitation falling onto the ground/water surface. It includes a few types of precipitation forms such as convective precipitation, large scale precipitation, liquid and solid precipitation. The amount is valid for the grid area and has the unit kg/m². The total precipitation is available only for the forecast time steps. It is an accumulated parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated precipitation over 24 hours. The total amount of rain might be computed by subtracting the snowfall water equivalent from the total precipitation.

Maximum 2m temperature since previous post-processing

It is the maximum air temperature at the height of 2 m above the surface since the last post-processing. The maximum 2m temperature is only available for the forecast time steps. The value is the maximum since the previous post-processing. For instance, for the first saved time step at forecast 1h it is the maximum surface air temperature, which occurred within the first hour of the forecast. For the second saved time step at forecast 2h, it is the maximum surface air temperature which happened in the second forecast hour, hence between fc1 and fc2. For longer forecasts, the output frequency is reduced. Hence, the maximum over a longer time period is saved. For instance, for the 15h forecast the maximum surface air temperature is identified within the period 12h – 15h since the last post-processing happened at 12h (12 hours after the onset of the forecast). The parameter is given in Kelvin [K].

Minimum 2m temperature since previous post-processing

It is the minimum air temperature at the height of 2 m above the surface since the last post-processing. The minimum 2m temperature is only available for the forecast time steps. The value is the minimum since the previous post-processing. For instance, for the first saved time step at forecast 1h it is the minimum surface air temperature, which occurred within the first hour of the forecast. For the second saved time step at forecast 2h, it is the minimum surface air temperature which happened in the second forecast hour, hence between fc1 and fc2. For longer forecasts, the output frequency is reduced. Hence, the minimum over a longer time period is saved. For instance, for the 15h forecast the minimum surface air temperature is identified within the period 12h – 15h since the last post-processing happened at 12-h (12 hours after the onset of the forecast). The parameter is given in Kelvin [K].

Skin temperature

The skin temperature is the model temperature valid for the grid area determined for the boundary surface to the atmosphere, both ground and water surfaces.  Skin temperature is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The parameter is given in Kelvin [K].

Surface latent heat flux

The surface latent heat flux is the exchange of latent heat (due to phase transitions: evaporation, condensation) with the surface (ground and water) through turbulent diffusion. It is the mean for the grid area.  By model convention downward fluxes are positive. Surface latent heat flux is only available for forecast time steps up to forecast hour sixThe surface direct solar radiation is the amount of direct solar (short-wave) radiation reaching the surface (ground and water). It is given as a mean for the grid area. The parameter is given in J/m². By model convention downward fluxes are positive. Surface direct solar radiation is only available for forecast time steps. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation heat flux over 24 hours.

Time-integrated surface net solar radiation

The parameter is given in J/m².

Surface sensible heat flux

The surface sensible heat flux is the exchange of heat (no phase transition) with The surface net solar radiation is the amount of solar (short-wave) radiation that is absorbed at the surface (ground and water) through turbulent diffusion. It is computed as
Surface net solar radiation = surface solar radiation downwards * (1 – albedo)
It is given as a mean for the grid area. The parameter is given in J/m². By model convention downward fluxes are positive. Surface net solar radiation sensible heat flux is only available for forecast time steps up to forecast hour six. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation heat flux over 24 hours. The parameter is given in J/m².

Time-integrated surface

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direct short-wave radiation

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The surface solar direct short-wave radiation downward is the amount of direct solar (short-wave) radiation reaching the surface (ground and water). It is given as a mean for the grid area. The parameter is given in J/m². By model convention downward By model convention downward fluxes are positive. Surface direct solar radiation downwards is only available for forecast time steps. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation over 24 hours. The parameter is given in J/m².

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Surface net solar radiation

The surface net thermal solar radiation is the difference between thermal (longamount of solar (short-wave) downward and upward radiation that is absorbed at the surface (ground and water) of the Earth. Thermal radiation is emitted by the atmosphere, clouds and the surface of the Earth. It is the . It is computed as
Surface net solar radiation = surface solar radiation downwards * (1 – albedo)
It is given as a mean for the grid area. The parameter is given in J/m². By model convention downward fluxes are positive. Surface net thermal solar radiation is only available for forecast time steps. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation over 24 hours. The parameter is given in J/m².

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Surface solar radiation downwards

The surface thermal solar radiation downward is the amount of thermal solar (longshort-wave) radiation reaching the surface (ground and water). It is given as a mean for the grid . The parameter is given in J/m². By area. By model convention downward fluxes are positive. Surface thermal solar radiation downwards is only available for forecast time steps. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation over 24 hours. The parameter is given in J/m².

Clear-sky net short-wave downward flux at the surface

Surface net thermal radiation

The surface net thermal radiation is the difference between thermal (long-wave) downward and upward radiation at the surface (ground and water) of the Earth. Thermal radiation is emitted by the atmosphere, clouds and This parameter is the amount of short-wave radiation from the Sun (also known as solar or direct radiation), which would be absorbed at the surface of the Earth assuming clear-sky (cloudless) conditions. It is computed as
Clear-sky net short-wave radiation = Clear-sky short-wave radiation downwards * (1 – albedo)
It is the mean for the grid area. By model convention downward fluxes are positive.
Clear-sky net short-wave Surface net thermal radiation is only available for forecast time steps. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation over 24 hours. The parameter is given in J/m². To convert to watts per square metre (W/m²), the accumulated values should be divided by the accumulation period expressed in seconds.

Clear-sky net long-wave downward flux at the surface

Surface thermal radiation downwards

The surface thermal radiation downward is the amount of thermal (long-wave) radiation reaching the surface (ground and water). It is given as a mean for the gridThe long-wave radiation (also known as thermal or terrestrial radiation) refers to radiation emitted by the atmosphere, clouds and the surface of the Earth. The clear-sky net long-wave radiation is the difference between downward and upward thermal radiation at the surface of the Earth, assuming clear-sky (cloudless) conditions. It is the mean for the grid area. By model convention downward fluxes are positive. Clear-sky net long-wave radiation Surface thermal radiation downwards is only available for forecast time steps. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated radiation over 24 hours. The parameter is given in J/m². To convert to watts per square metre (W/m²), the accumulated values should be divided by the accumulation period expressed in seconds.

Time integral of surface eastward momentum flux

Surface net solar radiation, clear sky

This parameter is the amount of solar radiation from the Sun (also known as short-wave or direct radiation), which would be absorbed at the surface of the Earth assuming clear-sky (cloudless) conditions. It is computed as
Clear-sky net solar radiation = Clear-sky solar radiation downwards * (1 – albedo)
It is the mean for the grid area. By model convention downward fluxes are positive.
Clear-sky net solar radiation is only available for forecast time stepsAir flowing over a surface exerts a stress that transfers momentum to the surface and slows the wind. Here, the parameter is the sum of all surface stress components, in an eastward direction. Momentum flux components are associated to orographic gravity waves, the turbulent interactions between the atmosphere and the surface, and to turbulent orographic form drag. For instance, the turbulent interactions between the atmosphere and the surface are due to the roughness of the surface. Positive (negative) values denote stress in the eastward (westward) direction. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated momentum fluxes radiation over 24 hours.
It is the mean for the grid. The parameter is given in N J/m-² s.

Time integral of surface northward momentum flux

. To convert to watts per square metre (W/m²), the accumulated values should be divided by the accumulation period expressed in seconds.

Surface net thermal radiation, clear sky

The thermal radiation (also known as long-wave or terrestrial radiation) refers to radiation emitted by the atmosphere, clouds and the surface of the Earth. The surface net thermal radiation is the difference between downward and upward thermal radiation at the surface of the Earth, assuming clear-sky (cloudless) conditions. It is the mean for the grid area. By model convention downward fluxes are positive. Surface net thermal radiation is only available for forecast time stepsAir flowing over a surface exerts a stress that transfers momentum to the surface and slows the wind. Here, the parameter is the sum of all surface stress components, in a northward direction. Momentum flux components are associated to orographic gravity waves, the turbulent interactions between the atmosphere and the surface, and to turbulent orographic form drag. For instance, the turbulent interactions between the atmosphere and the surface are due to the roughness of the surface. Positive (negative) values denote stress in the northward (southward) direction. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated momentum fluxes radiation over 24 hours. It is the mean for the grid area. The parameter is given in N J/m-² s.

Mean sea level pressure

The mean sea level pressure is the air pressure reduced to mean sea level valid for the grid area. The parameter is given in Pascal [Pa]. Mean sea level pressure is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Surface pressure

The surface pressure is the air pressure at the surface (ground and water) valid for the grid area. The parameter is given in Pascal [Pa]. Mean sea level pressure is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

High cloud cover

The high cloud cover is the percentage of sky covert with clouds in high altitude. It is valid for the grid area and high refers to height above 5000m. The parameter is given in %. High cloud cover is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Low cloud cover

The low cloud cover is the percentage of sky covert with clouds in low altitude. It is valid for the grid area and low altitude refers to heights below 2500m. The parameter is given in %. Low cloud cover is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Medium cloud cover

. To convert to watts per square metre (W/m²), the accumulated values should be divided by the accumulation period expressed in seconds.

Momentum flux at the surface u-component

Air flowing over a surface exerts a stress that transfers momentum to the surface and slows the wind. Here, the parameter is the sum of all surface stress components, in an eastward direction. Momentum flux components are associated to orographic gravity waves, the turbulent interactions between the atmosphere and the surface, and to turbulent orographic form drag. For instance, the turbulent interactions between the atmosphere and the surface are due to the roughness of the surface. Positive (negative) values denote stress in the eastward (westward) direction. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated momentum fluxes over 24 hours.
It is the mean for the grid. The parameter is given in N m^-2 s.

Momentum flux at the surface v-component

Air flowing over a surface exerts a stress that transfers momentum to the surface and slows the wind. Here, the parameter is the sum of all surface stress components, in a northward direction. Momentum flux components are associated to orographic gravity waves, the turbulent interactions between the atmosphere and the surface, and to turbulent orographic form drag. For instance, the turbulent interactions between the atmosphere and the surface are due to the roughness of the surface. Positive (negative) values denote stress in the northward (southward) direction. It is an accumulated (time-integrated) parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated momentum fluxes over 24 hours. It is the mean for the grid area. The parameter is given in N m^-2 s.

Mean sea level pressure

The mean sea level pressure is the air pressure reduced to mean sea level valid for the grid area. The parameter is given in Pascal [Pa]. Mean sea level pressure The medium cloud cover is the percentage of sky covert with clouds in medium altitude. It is valid for the grid area, and medium altitude refers to heights between 2500m through 5000m. The parameter is given in %. Medium cloud cover is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Total cloud cover

Surface pressure

The surface pressure is the air pressure at the surface (ground and water) Total cloud cover is the percentage of sky covert with clouds. It is valid for the grid area, and clouds at any height above the surface are considered. The parameter is given in %. Total cloud cover Pascal [Pa]. Mean sea level pressure is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow density

High cloud cover

The high cloud cover is the percentage of sky covert with clouds in high altitude. It is valid for the grid area and high refers to height above 5000m. The parameter is given in %. High cloud cover Snow density is the snow mass per unit of volume. Hence, the parameter is given in kg/m³. It is given as the mean for the grid area. Grid points without snow have missing values. Snow density is available for the analysis and the forecast time steps up to forecast hour six. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow depth

Low cloud cover

The low cloud cover is the percentage of sky covert with clouds in low altitude. It is valid Snow depth is the average snow height for the grid area . Snow depth and low altitude refers to heights below 2500m. The parameter is given in metre [m]. Snow depth %. Low cloud cover is available for the analysis and the forecast time steps. The For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow depth water equivalent

Medium cloud cover

The medium cloud cover is the percentage of sky covert with clouds in medium altitude. It is valid for the grid area, and medium altitude refers to heights between 2500m through 5000m. The parameter is given in %. Medium cloud cover Snow depth water equivalent expresses the snow depth in kg of snow over one square metre [kg/m²]. The unit corresponds to 1 mm of water equivalent. It is given as the mean for the grid area. Snow depth water equivalent is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow fall water equivalent

Snow fall water equivalent expresses the snow fall in kg of snow over one square metre [kg/m²]. The unit corresponds to 1 mm of water equivalent. It is given as the mean for the grid. Snow fall water equivalent is only available for the forecast time steps. It is an accumulated parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated snow fall water equivalent over 24 hours.

Land-Sea mask

The land-sea mask is a field that contains, for every grid, the proportion of land in the grid box. The parameter is dimensionless and the values are between 0 (sea) and 1 (land). The land-sea mask is constant in time and the field is available for every analysis.

Orography

The orography is the height of the terrain with respect to the model defined globe. Each grid point has one value representing the mean over the grid point domain. The orography is given as geopotential height in metre [gpm]. The orography is constant in time and the field is available for every analysis.

Surface roughness

Total cloud cover

Total cloud cover is the percentage of sky covert with clouds. It is valid for the grid area, and clouds at any height above the surface are considered. The parameter is given in %. Total cloud cover is available for the analysis and the forecast time steps. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow density

Snow density is the snow mass per unit of volume. Hence, the parameter is given in kg/m³. It is given as the mean for the grid area. Grid points without snow have missing values. Snow density is available for the analysis and the forecast time steps up to forecast hour six. For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow depth

Snow depth is the average snow height for the grid area. Snow depth is given in metre [m]. Snow depth is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snow depth water equivalent

Snow depth water equivalent expresses the snow depth in kg of snow over one square metre [kg/m²]. The unit corresponds to 1 mm of water equivalent. It is given as the mean for the grid area. Snow depth water equivalent is The surface roughness describes the aerodynamic roughness length (over land). Each grid point has one value representing the mean over the grid point. The surface roughness is given in metre [m]. The effective surface roughness is depending on the orographic component (constant part), the snow depth, the evolution of the Leaf Area Index and the fraction of vegetation, which is different for each month. Surface roughness is available for the analysis and the forecast time steps.  

Soil temperature

The soil temperature is the model temperature valid for the grid area at the corresponding soil layer. The parameter is given in Kelvin [K]. The parameter is available for analysis and forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The soil model has three layers but only data for the top layer, closest to the surface, are provided. Deeper layers are affected by spin-up effects at the seams of the production streams. Users interested in soil parameters are recommended to use CERRA-Land data.

Liquid Volumetric soil moisture

The liquid volumetric soil water is the amount of non-frozen water in a cubic metre soil valid for the grid area in the corresponding soil layer. The parameter is given in m³/m³. The parameter is available for analysis and forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The soil model has three layers but only data for the top layer, closest to the surface, are provided. Deeper layers are affected by spin-up effects at the seams of the production streams. Users interested in soil parameters are recommended to use CERRA-Land data.

Volumetric soil moisture

For the forecast, the value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Snowfall water equivalent

Snowfall water equivalent expresses the snowfall in kg of snow over one square metre [kg/m²]. The unit corresponds to 1 mm of water equivalent. It is given as the mean for the grid. Snowfall water equivalent is only available for the forecast time steps. It is an accumulated parameter meaning that it is accumulated from the beginning of the forecast. For instance, the 24-h forecast has the accumulated snowfall water equivalent over 24 hours.

Land-Sea mask

The land-sea mask is a field that contains, for every grid, the proportion of land in the grid box. The parameter is dimensionless and the values are between 0 (sea) and 1 (land). The land-sea mask is constant in time and the field is available for every analysis.

Orography

The orography is the height of the terrain with respect to the model defined globe. Each grid point has one value representing the mean over the grid point domain. The orography is given as geopotential height in metre [m²/s²]. The orography is constant in time and the field is available for every analysis.

Surface roughness

The surface roughness describes the aerodynamic roughness length (over land). Each grid point has one value representing the mean over the grid point. The surface roughness is given in metre [m]. The effective surface roughness is depending on the orographic component (constant part), the snow depth, the evolution of the Leaf Area Index and the fraction of vegetation, which is different for each month. Surface roughness is available for the analysis and the forecast time steps. 

Soil temperature

The soil temperature is the model temperature valid for the grid area at the corresponding soil layer. The parameter is given in Kelvin [K]. The parameter is available for analysis and forecast time steps. The value is instantaneous meaning that it is valid for the last time The volumetric soil moisture is the sum of the liquid and frozen water in a cubic metre soil valid for the grid area in the corresponding soil layer. The parameter is given in m³/m³. The parameter is available for analysis and forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The soil model has three layers but only data for the top layer, closest to the surface, are provided. Deeper layers are affected by spin-up effects at the seams of the production streams. Users interested in soil parameters are recommended to use CERRA-Land data.

Parameters on height levels

...

Metadata

...

Horizontal coverage

...

The model domain spans from northern Africa beyond the northern tip of Scandinavia. In the west it ranges far into the Atlantic Ocean and in the east it reaches to the Ural Mountains. Herewith, it covers entire Europe.
See Figure 2 for an overview of the model domain.

...

Horizontal resolution

...

5.5 km x 5.5 km

...

Vertical coverage

...

11 height levels

...

Vertical levels

...

15m, 30m, 50m, 75m, 100m, 150m, 200m, 250m, 300m, 400m, 500m

...

Temporal coverage

...

1984-09-01 00 UTC – 2021-06-30 21 UTC

...

Temporal resolution

...

Analyses are available at 00, 03, 06, 09, 12, 15, 18, and 21 UTC.
The forecast length is depending on the cycle.
Cycles initialized at 00 and 12 UTC have forecasts saved at 1, 2, 3, 4, 5, 6, 9, 12, 15, 18, 21, 24, 27, and 30.
All other cycles have forecasts saved at 1, 2, 3, 4, 5, and 6.
Some parameters are saved only until forecast hour six.
See section 4.1.3 (Fig. 7) for more details.

...

Data type and format

...

Gridded data in GRIB2

...

Grid

...

Lambert conformal conic grid with 1069x1069 grid points

Liquid Volumetric soil moisture (non-frozen)

The liquid volumetric soil water is the amount of non-frozen water in a cubic metre soil valid for the grid area in the corresponding soil layer. The parameter is given in m³/m³. The parameter is available for analysis and forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The soil model has three layers but only data for the top layer, closest to the surface, are provided. Deeper layers are affected by spin-up effects at the seams of the production streams. Users interested in soil parameters are recommended to use CERRA-Land data.

Volumetric soil moisture

The volumetric soil moisture is the sum of the liquid and frozen water in a cubic metre soil valid for the grid area in the corresponding soil layer. The parameter is given in m³/m³. The parameter is available for analysis and forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The soil model has three layers but only data for the top layer, closest to the surface, are provided. Deeper layers are affected by spin-up effects at the seams of the production streams. Users interested in soil parameters are recommended to use CERRA-Land data.

Parameters on height levels

Wind speed

Wind speed is the wind speed valid for the grid area determined for a certain height (15m-500m) above the surface. The parameter is given in m/s.

...

Parameter

...

Unit

...

GRIB code

...

Analysis 3 hourly

...

forecast
1,2,3,…

...

1.

...

Wind speed

...

m/s

...

10

...

yes

...

yes

...

2.

...

Wind direction

...

degrees

...

3031

...

yes

...

yes

...

3.

...

Pressure

...

Pa

...

54

...

yes

...

yes

...

4.

...

Relative humidity

...

%

...

157

...

yes

...

yes

...

5.

...

Temperature

...

K

...

130

...

yes

...

yes

...

6.

...

Specific cloud liquid water content

...

kg/kg

...

246

...

-

...

yes

...

7.

...

Specific cloud ice water content

...

kg/kg

...

247

...

-

...

yes

...

8.

...

Specific rain water content

...

kg/kg

...

75

...

-

...

yes

...

9.

...

Specific snow water content

...

kg/kg

...

76

...

-

...

yes

...

10.

...

Turbulent kinetic energy

...

J/kg

...

260155

...

-

...

yes

Wind speed

Wind speed is the wind speed valid for the grid area determined for a certain height (15m-500m) above the surface. The parameter is given in m/s. It is computed from both the zonal (u) and the meridional (v) wind components by wind speed=u²+v². The wind speed is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Wind direction

The wind direction is the wind direction valid for the grid area determined for a certain height (15m-500m) above the surface. The parameter is given in degrees ranging from 0-360. Here, 0° means a northerly wind and 90° indicates an easterly wind. The wind direction is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Pressure

The pressure is the air pressure at a certain height (15m-500m) above the surface valid for the grid area. The parameter is given in Pascal \[Pa\]. The pressure is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Relative humidity

The relative humidity is the modelled humidity valid for the grid area determined at a certain height (15m-500m) above the surface. The parameter is given % ranging from 0-100. 0% means that the air is totally dry whereas 100% indicates that the air is saturated with water vapour. The saturation is defined with respect to saturation of the mixed phase, i.e. with respect to saturation over ice below -23°C and with respect to saturation over water above 0°C. In the regime in between a quadratic interpolation is applied. Surface air relative humidity is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Temperature

The temperature is the air temperature valid for the grid area determined at a certain height (15m-500m) above the surface. The parameter is given in Kelvin [K]. The temperature is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. 

Specific cloud liquid water content

Specific cloud liquid water content is the grid-box mean liquid water content (mass of condensate / mass of moist air) on a height level. It is given in kg/kg. The parameter is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific cloud ice water content

Specific cloud ice water content is the grid-box mean ice water content (mass of condensate / mass of moist air) on a height level. It is given in kg/kg. The parameter is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific rain water content

The mass of water that is of raindrop size and so can fall to the surface as precipitation. The quantity is expressed in kilograms per kilogram of the total mass of moist air. The 'total mass of moist air' is the sum of the dry air, water vapour, cloud liquid, cloud ice, rain and falling snow. This parameter represents the average value for a grid box. Clouds contain a continuum of different sized water droplets and ice particles. The parameter is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific snow water content

The mass of snow (aggregated ice crystals) that can fall to the surface as precipitation. The mass is expressed in kilograms per kilogram of the total mass of moist air. The 'total mass of moist air' is the sum of the dry air, water vapour, cloud liquid, cloud ice, rain and falling snow. This parameter represents the average value for a grid box. Clouds contain a continuum of different sized water droplets and ice particles. The parameter is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Turbulent kinetic energy

The turbulent kinetic energy is the mean kinetic energy per unit mass associated with eddies in turbulent flow. This parameter describes the turbulent kinetic energy at a certain height (15m-500m) above the surface and is valid for the grid area. It is given in J/kg. The turbulent kinetic energy is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Parameters on pressure levels

Cloud cover

Cloud cover is the percentage of sky covert with clouds. It is valid for the grid at the corresponding height. The parameter is given in %. Total cloud cover is only available for the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific cloud liquid water content

The specific cloud liquid water content is the grid-box mean mass of condensate / mass of moist air on a pressure level. The parameter is given in kg/kg. Specific cloud liquid water content is only available for the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific cloud ice water content

The specific cloud ice water content is the grid-box mean mass of condensate / mass of moist air on a pressure level. The parameter is given in kg/kg. Specific cloud ice water content is only available for the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific rain water content

The mass of water that is of raindrop size and so can fall to the surface as precipitation. The quantity is expressed in kilograms per kilogram of the total mass of moist air. The 'total mass of moist air' is the sum of the dry air, water vapour, cloud liquid, cloud ice, rain and falling snow. This parameter represents the average value for a grid box. Clouds contain a continuum of different sized water droplets and ice particles. The parameter is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Specific snow water content

The mass of snow (aggregated ice crystals) that can fall to the surface as precipitation. The mass is expressed in kilograms per kilogram of the total mass of moist air. The 'total mass of moist air' is the sum of the dry air, water vapour, cloud liquid, cloud ice, rain and falling snow. This parameter represents the average value for a grid box. Clouds contain a continuum of different sized water droplets and ice particles. The parameter is only available for forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Turbulent kinetic energy

The turbulent kinetic energy is the mean kinetic energy per unit mass associated with eddies in turbulent flow. This parameter describes the turbulent kinetic energy at a pressure level and it is valid for the grid area. It is is given in J/kg.The turbulent kinetic energy is only available the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Relative humidity

The relative humidity is the modelled humidity valid for the grid area at the corresponding height. The parameter is given in % ranging from 0-100. 0% means that the air is totally dry whereas 100% indicates that the air is saturated with water vapour. The saturation is defined with respect to saturation of the mixed phase, i.e. with respect to saturation over ice below -23°C and with respect to saturation over water above 0°C. In the regime in between a quadratic interpolation is applied. Relative humidity is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. Please check section 2.3, Model specific issues, when using this parameter.

Temperature

The temperature is the model temperature valid for the grid area at the corresponding height. The parameter is given in Kelvin [K]. Temperature is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The parameter is given in Kelvin [K].

U-component of wind

The U-component of wind or U-velocity is the zonal component of the wind valid for the grid area at the corresponding height. The parameter is given in m/s. By model convention westerly wind (blowing from the west to the east) are positive. U-velocity is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The parameter is given in m/s.

V-component of wind

The V-component of wind or V-velocity is the meridional component of the wind valid for the grid area at the corresponding height. The parameter is given in m/s. By model convention southerly wind (blowing from the south to the north) are positive. V-velocity is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step. The parameter is given in m/s.

Geopotential

The geopotential is the potential energy of unit mass at this pressure level relative to the sea level. It is valid for the grid area and it is given in m²/s². The geopotential is available for the analysis and the forecast time steps. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Parameters on model levels

Table 4: Overview of parameters on model levels

Specific humidity

The specific humidity is the mass of water vapour per unit mass of air valid for the grid area at the corresponding model level. Only analyses are stored for parameters on model levels. The parameter is given in kg/kg.

Temperature

The temperature is the model temperature valid for the grid area at the corresponding model level. Only analyses are stored for parameters on model levels. The parameter is given in Kelvin [K]. Temperature given in Kelvin can be converted to degrees Celsius (°C) by subtracting 273.15.

U-component of wind

The U-component of wind is the zonal component of the wind valid for the grid area at the corresponding model level. By model convention westerly wind (blowing from the west to the east) are positive. Only analyses are stored for parameters on model levels. The parameter is given in m/s.

V-component of wind

The V-component of wind is the meridional component of the wind valid for the grid area at the corresponding model level. By model convention southerly wind (blowing from the south to the north) are positive. Only analyses are stored for parameters on model levels. The parameter is given in m/s.

The CERRA grid description

Below are the essential parameters describing the grid and the used Lambert Conformal Conic projection. More information about the grid and coordinates can be found in the FAQ.
Number of points along x-axis: 1069
Number of points along y-axis: 1069
X-direction grid length: 5500 m
Y-direction grid length: 5500 m
Projection: Lambert Conformal Conic
Central meridian: 8
Standard parallel 1: 50
Standard parallel 2: 50
Latitude of origin: 50
Earth assumed spherical with radius: 6371229 m

...

CERRA-EDA

CERRA-EDA comprises the same domain as CERRA and has exactly the same set of parameters as the high-resolution CERRA dataset. It differs only in the horizontal resolution, which is 11km as well as in the number of available time steps. CERRA-EDA has four analyses per day, at 00, 06, 12 and 18 UTC. Starting from the analyses, forecasts are run for six hours. Forecast fields are saved with hourly resolution.

Parameters on model levels

...

Parameter

...

Unit

...

GRIB code

...

Analysis 3 hourly

...

forecast
1,2,3,…

...

1.

...

Specific humidity

...

kg/kg

...

133

...

yes

...

-

...

2.

...

Temperature

...

K

...

130

...

yes

...

-

...

3.

...

U-velocity

...

m/s

...

131

...

yes

...

-

...

4.

...

V-velocity

...

m/s

...

132

...

yes

...

-

Specific humidity

The specific humidity is the mass of water vapour per unit mass of air valid for the grid area at the corresponding model level. The parameter is given in kg/kg. Only analyses are stored for parameters on model levels. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

Temperature

The temperature is the model temperature valid for the grid area at the corresponding model level. The parameter is given in Kelvin [K]. Only analyses are stored for parameters on model levels. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

U-component of wind

The U-component of wind is the zonal component of the wind valid for the grid area at the corresponding model level. The parameter is given in m/s. By model convention westerly wind (blowing from the west to the east) are positive. Only analyses are stored for parameters on model levels. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

V-component of wind

The V-component of wind is the meridional component of the wind valid for the grid area at the corresponding model level. The parameter is given in m/s. By model convention southerly wind (blowing from the south to the north) are positive. Only analyses are stored for parameters on model levels. The value is instantaneous meaning that it is valid for the last time step of the integration at the issued time step.

The CERRA grid description

Below are the essential parameters describing the grid and the used Lambert Conformal Conic projection. More information about the grid and coordinates can be found in the FAQ.
Number of points along x-axis: 1069
Number of points along y-axis: 1069
X-direction grid length: 5500 m
Y-direction grid length: 5500 m
Projection: Lambert Conformal Conic
Central meridian: 8
Standard parallel 1: 50
Standard parallel 2: 50
Latitude of origin: 50
Earth assumed spherical with radius: 6371229 m

...

Latitude and longitude of the corner grid points in decimal degrees

...

Grid point

...

Latitude

...

Longitude

...

Upper-left

...

63.7695

...

-58.1051

...

Upper-right

...

63.7695

...

74.1051

...

Lower-right

...

20.2923

...

33.4859

...

Lower-left

...

20.2923

...

-17.4859

CERRA-EDA

CERRA-EDA comprises the same domain as CERRA and has exactly the same set of parameters as the high-resolution CERRA dataset. It differs only in the horizontal resolution, which is 11km as well as in the number of available time steps. CERRA-EDA has four analyses per day, at 00, 06, 12 and 18 UTC. Starting from the analyses, forecasts are run for six hours. Forecast fields are saved with hourly resolution.

...

Metadata for CERRA-EDA parameters

...

Horizontal coverage

...

Same as CERRA.
See section 3.1 as well as Figure 2 for an overview of the model domain.

...

Horizontal resolution

...

11 km x 11 km

...

Vertical coverage

...

Same as for CERRA parameters.

...

Vertical resolution

...

Same as for CERRA-parameters.

...

Temporal coverage

...

Same as for CERRA.

...

Temporal resolution

...

Analyses are available at 00, 06, 12, and 18 UTC.
The forecast length is six hours for all cycles and forecasts are saved with hourly resolution.

...

Data type and format

...

Gridded data in GRIB2

...

Grid

...

Lambert conformal conic grid with 565x565 grid points

The CERRA-EDA grid description

Below are the essential parameters describing the CERRA-EDA grid and the used Lambert Conformal Conic projection. More information about the grid and coordinates can be found in the FAQ in section 2.3.
Number of points along x-axis: 565
Number of points along y-axis: 565
X-direction grid length: 11000 m
Y-direction grid length: 11000 m
Projection: Lambert Conformal Conic
Central meridian: 8
Standard parallel 1: 48
Standard parallel 2: 48
Latitude of origin: 48
Earth assumed spherical with radius: 6371229 m

Known issues

Wrong metadata for the 2m maximum and minimum temperature

The metadata for the forecast step range is incorrect in the GRIB2 files for the maximum 2m temperature since previous post-processing and the minimum 2m temperature since previous post-processing. The correct step range is given in the table below.

Minor data assimilation issues (issues when some observations were not available)

Observational data is the backbone information source of a reanalysis system. However, during the course of reanalysis, for various technical reasons, some of the data streams got left out. In many cases this is only discovered after the reanalysis has been run.  It can also occur that instances in which some radiance data, that should have been blacklisted, are used. Whenever it is possible and the impact is judged to be of significance, the affected periods have been rerun. However, reruns have not been performed for periods with only minor issues in the observational data streams. This has been decided largely based on experiences from verification and real time monitoring. If the impact has been judged to be relatively insignificant, and not to affect the overall consistence and integrity of the CERRA or CERRA-EDA reanalysis, reruns have not been performed.

For completeness, a list of the occurrences of missing observational data and affected periods are listed below. 

The CERRA-EDA grid description

Below are the essential parameters describing the CERRA-EDA grid and the used Lambert Conformal Conic projection. More information about the grid and coordinates can be found in the FAQ in section 2.3.
Number of points along x-axis: 565
Number of points along y-axis: 565
X-direction grid length: 11000 m
Y-direction grid length: 11000 m
Projection: Lambert Conformal Conic
Central meridian: 8
Standard parallel 1: 48
Standard parallel 2: 48
Latitude of origin: 48
Earth assumed spherical with radius: 6371229 m

...

Latitude and longitude of the corner grid points in decimal degrees

...

Grid point

...

Latitude

...

Longitude

...

Upper-left

...

63.4028

...

-60.4047

...

Upper-right

...

63.4028

...

76.4047

...

Lower-right

...

17.6121

...

34.3203

...

Lower-left

...

17.6121

...

-18.3203

References

• Bazile E, R. Abida, A. Verelle, P. Le Moigne and C. Szczypta (2017): MESCAN-SURFEX surface analysis, deliverable D2.8 of the UERRA project, http://www.uerra.eu/publications/deliverable-reports.html
• El-Said A., P. Brousseau, M. Ridal and R. Randriamampianina (2021): A new temporally flow-dependent EDA estimating background errors in the new Copernicus European Regional Re-Analysis (CERRA), Earth and Space Science Open Archive, pp. 28, doi 10.1002/essoar.10507207.1, https://doi.org/10.1002/essoar.10507207.1
• Niermann D. et al. (2017): Scientific report on assessment of regional analysis against independent data sets, deliverable D3.6 of the UERRA project, http://www.uerra.eu/publications/deliverable-reports.html
• Ridal M., S. Schimanke and S. Hopsch (2018): Documentation of the RRA system: UERRA (C3S deliverable D322_Lot1.1.1.2, Documenting the UERRA system)
• Soci C., E. Bazile, F. Besson and T. Landelius (2016). High-resolution precipitation re-analysis system for climatological purposes. Tellus A, Dynamic Meteorology and Oceanography, 68:1, DOI: 10.3402/tellusa.v68.29879
• Verver Gé (2017): User Guidance, deliverable D8.4 of the UERRA project, http://www.uerra.eu/publications/deliverable-reports.html

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