This page contains a few rules on the UERRA parameters. A complete list of all the parameters and GRIB2 encoding is given here.

UERRA parameters rules

Units

Accumulations

Instantaneous fields

Parameters archived since previous post-processing

Fluxes

Missing values

Grid and resolution

Types of forecasts

GRIB2 encoding

ECMWF encoding/decoding Software

ECMWF makes available a GRIB decoding library (GRIB-API) for the benefit of the WMO community. GRIB-API can be freely downloaded from here and the documentation can be found here. The GRIB-API provides a simplified access to GRIB2 headers through a set of virtual keys documented her

The version of GRIB-API which can recognise all UERRA parameters is currently under development and should be released to some extent by the 1st half of June. Until then please use the version 1.15.0 which can identify UERRA products as per below (paragraph 1).

 

Encoding

1) UERRA production status of processed data

The WMO has added two values to table 1.3 Production status of data:

Section 1
Octets Key nameUERRA operational productsUERRA test products
20productionStatusOfProcessedData89

2) Deterministic and ensemble data assimilation forecasts

Two types of datasets are expected for UERRA - outputs from deterministic and ensemble data assimiliation systems. How they should be encoded in GRIB2 is shown below.

Control and perturbed forecasts are identified in section 1 and 4. The following tables explains how to code them in GRIB2:

Both systems - deterministic and ensemble DA (analysis or forecast products)
Section 1
OctetsKey nameAnalysis productsForecast products
21typeOfProcessedData01
Deterministic system (both analysis and forecast products)
Section 4
OctetsKey name

Analysis and Forecast products (instantaneous)

Analysis and Forecast products (statisticially processed = accumulated/min/max values )

8-9productDefinitionTemplateNumber

0

(Analysis or forecast at a horizontal level or in a horizontal layer at a point in time (grib2/tables/17/4.0.table))

8

(Average, accumulation, extreme values or other statistically processed values at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval (grib2/tables/17/4.0.table))

Ensembe DA system (both analysis and forecast products)
Section 4
OctetsKey name

Analysis and Forecast products (instantaneous)

Analysis and Forecast products (statisticially processed = accumulated/min/max values )

8-9productDefinitionTemplateNumber

1

(Individual ensemble forecast, control and perturbed, at a horizontal level or in a horizontal layer at a point in time  (grib2/tables/17/4.0.table))

11

(Individual ensemble forecast, control and perturbed, at a horizontal level or in a horizontal layer, in a continuous or non-continuous time interval (grib2/tables/17/4.0.table))

Ensemble (section 4, template 4.61)
Octets Example for 2nd eps member of ensemble with 4 members (0/1/2/3)
35type of ensemble forecast255 (missing) 
36perturbation number2
37number of forecasts in ensemble4

3) Time component of GRIB2 definition

Examples of GRIB2 files

 deterministicensemble DA
 ANFCANFC
Accumulations    
Instantaneous    
Maximum since previous post-processing    
Minimum since previous post-processing  
Parameter on soil level

grib

dump

grib

dump

Parameter on soil layer